Envoy
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Path-based RBAC authorization bypass in Envoy Proxy lets an unauthenticated remote client reach protected backends such as /admin by appending a semicolon path parameter (e.g. /admin;x), because the router strips that suffix before route matching while the RBAC url_path matcher evaluates the untouched raw path. Exploitation is tightly gated rather than default: it requires a route configured with ignore_path_parameters_in_path_matching, a path-based RBAC rule (PathMatcher or UriTemplateMatcher) guarding the protected path, and a crafted request that still selects the protected route after stripping. All releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected; the vendor has published fixed releases, and no public exploit code or confirmed active exploitation (CISA KEV) was identified at time of analysis.
Stored cross-site scripting in Envoy Proxy's admin statistics page lets an attacker run script in the admin interface's origin: the /stats?format=html endpoint (StatsHtmlRender) sanitizes statistic values but emits statistic names raw, so a data-plane component that folds attacker-supplied request path segments into dynamic stat names - notably grpc_stats with stats_for_all_methods enabled - can persist a script-bearing name that fires when an operator opens the page in a browser. Every release before 1.36.10, 1.37.6, 1.38.4, and 1.39.1 is affected; the independently assessed vector is CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N (7.4), i.e. unauthenticated remote influence over the injected text but multiple gating prerequisites plus required operator interaction, with impact scoped to the admin origin where privileged same-origin requests can then be issued. No public exploit code has been identified at time of analysis and the CVE is not listed in CISA KEV; exploitation is realistic only where the admin HTML endpoint is browser-reachable and a dynamic-stat-generating component is enabled.
Envoy Proxy releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 can be crashed by a remote, unauthenticated attacker through its HTTP/3 datagram and Capsule Protocol handling (prerequisites: PR:N, no user interaction). When a request enters a stream-recreation path such as an internal redirect, the HttpDatagramHandler keeps a cached pointer to the original RequestDecoder; a subsequent HTTP/3 datagram invokes decodeData through that freed decoder, producing invalid virtual dispatch and process termination (CWE-416 use-after-free, CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H). Exploitation is gated on a non-default configuration - HTTP/3 (QUIC) downstream plus Capsule Protocol enabled, e.g. MASQUE connect-udp tunneling - combined with an internal-redirect route and precise frame sequencing; no public exploit code or CISA KEV entry was identified at time of analysis.
Unauthenticated remote attackers can exhaust memory and trigger an out-of-memory kill of Envoy Proxy by sending HTTP/2 requests that include a large Host header alongside an existing :authority pseudo-header, since the discarded Host value is copied but never charged against header size or count limits, and HPACK dynamic-table indexing lets an attacker repeatedly reference that large value across a bounded number of streams. All Envoy releases before 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected, including both the nghttp2 and oghttp2 HTTP/2 codec implementations, and the flaw is reachable on any listener that terminates HTTP/2 with no authentication or user interaction required (CVSS 3.1 base 7.5, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, CWE-401). No public exploit code and no confirmed active exploitation have been identified at time of analysis, but the low complexity and lack of prerequisites make this a practical availability risk for internet-facing edge proxies; note the supplied "Authentication Bypass" tag is misleading - the impact is availability-only, with no confidentiality or integrity loss.
Unauthenticated remote clients can crash Envoy Proxy by sending a path-less CONNECT request when the ext_authz HTTP filter is configured to apply query_parameters_to_set or query_parameters_to_remove mutations and the external authorization service returns such a mutation. The crash is a null-pointer dereference in the ext_authz filter's Filter::onComplete path, producing a denial of service (CVSS 7.5, A:H) against the affected proxy process; impact is limited to availability, with no confidentiality or integrity loss. Exploitation is gated by two non-default configuration prerequisites - accepting path-less CONNECT and enabling ext_authz query-parameter mutation - and no public exploit code has been identified at time of analysis.
Denial of service in Envoy Proxy releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, where the optional oghttp2 upstream HTTP/2 codec accepts a response trailer HEADERS frame that lacks the END_STREAM flag, causing Envoy to complete and deferred-delete the ActiveRequest while oghttp2 keeps the stream open. The resulting dangling reference in ClientStreamImpl (response_decoder_) can be dereferenced by a subsequent frame on that stream, freeing-then-using memory and crashing the Envoy process (CWE-20, CVSS 3.1 7.5, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - assessed independently at AC:H). Exploitation is remote and unauthenticated once preconditions hold, but it is limited to non-default configurations: the oghttp2 upstream codec must be explicitly enabled, the malformed trailers must be emitted by the upstream server Envoy proxies to (an attacker-controlled or compromised upstream, or injected frames on that connection), and the default nghttp2 codec rejects the malformed trailers outright. Vendor patches are available (1.36.10, 1.37.6, 1.38.4, 1.39.1); no public exploit code was identified and the issue is not in CISA KEV at time of analysis.
An access-control bypass in Envoy Proxy (all versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1) allows unauthenticated remote clients to reach routes that HTTP RBAC policies were configured to deny, resulting in disclosure of protected content. The flaw only materializes when a NEGATIVE (DENY) policy uses a safe_regex matcher against header values and a byte-oriented route matcher independently reads the raw header bytes; positive ALLOW regexes fail closed and exact, prefix, suffix, and contains matchers are unaffected. No public exploit code has been identified at time of analysis, and the vendor has released fixed versions, so real-world risk is driven almost entirely by whether a deployment uses that specific safe_regex-in-negative-policy configuration.
Request smuggling in Envoy Proxy allows an unauthenticated HTTP/2 client to embed a complete HTTP/1.1 request inside the data payload of an extended CONNECT (a generic, non-WebSocket HTTP upgrade) so that Envoy forwards that payload upstream before the upstream has accepted the upgrade, writes it unframed to a keep-alive HTTP/1.1 upstream, and returns the upstream socket to the shared pool with a smuggled response still queued - meaning a different, unrelated downstream client can subsequently be served the attacker's response. Every Envoy release prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 is affected, but exploitation is configuration-dependent: the listener must proxy a generic non-WebSocket upgrade to an HTTP/1.1 upstream with backend keep-alive enabled, shared (non-per-downstream) connection pools, and max_requests_per_connection not set to 1; WebSocket upgrades, plain CONNECT, disabled backend keep-alive, per-downstream pools, and max_requests_per_connection=1 are explicitly out of scope for the demonstrated path. No public exploit code has been identified at time of analysis, and this CVE is not listed in CISA KEV.
Denial of service in Envoy proxy versions 1.37.0 through 1.37.4 and 1.38.x before 1.38.3 lets remote attackers crash the proxy by sending a request that omits the Host header when access logging is configured with the %REQUESTED_SERVER_NAME(X:Y)% operator using host-related options (e.g. HOST_FIRST, SNI_FIRST). The missing header triggers a null pointer dereference (CWE-476), taking down the data-plane proxy and any traffic flowing through it. No public exploit identified at time of analysis and the issue is not in CISA KEV.
Heap buffer overflow in Envoy's TcpStatsdSink component (versions 1.34.0 through pre-fix releases) allows unauthenticated remote attackers to crash the Envoy process or potentially achieve remote code execution by submitting HTTP or gRPC requests with request paths exceeding 16KiB, provided a specific non-default dual-filter configuration is present. The root flaw is an incorrect buffer rotation in the thread-local metric flusher that allocates a new 16KiB slice but continues writing beyond its boundary via unchecked memcpy operations. No public exploit has been identified at time of analysis, though vendor-confirmed patches are available across all affected release branches (1.35.13, 1.36.9, 1.37.5, 1.38.3).
The envoy.filters.http.grpc_stats HTTP filter in Envoy versions 1.26.0 through the pre-fix releases crashes with a null pointer dereference when a Connect protocol request (Content-Type: application/connect+proto or application/connect+json) is routed to a direct_response route, terminating the Envoy process entirely. The vendor description states a single unauthenticated HTTP request is sufficient to trigger the crash, giving any network-reachable attacker a trivial one-packet denial of service against affected deployments. No confirmed active exploitation (absent from CISA KEV) and no public exploit code has been identified at time of analysis, but the trivial trigger condition makes this high practical risk for any deployment with both preconditions present.
Null pointer dereference in Envoy's router filter crashes the entire proxy process, terminating all active connections, when body-less non-GET/HEAD requests (POST, PUT, DELETE, PATCH) encounter an upstream HTTP 303 response on a route configured with internal redirect policy. Affected versions span 1.18.0 through the fixes released in branches 1.35.13, 1.36.9, 1.37.5, and 1.38.3. An unauthenticated remote attacker who can influence upstream response codes or reach a vulnerable route configuration can cause complete denial of service; no public exploit identified at time of analysis and no CISA KEV listing.
HTTP request smuggling in Envoy proxy (versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1) lets remote attackers desynchronize HTTP/1 upstream connections by sending an HTTP/3 downstream request that is transport-complete (HEADERS with FIN) yet declares a nonzero Content-Length, leaving the translated HTTP/1 request with unresolved body debt. When the HTTP/1 origin replies before reading the body and keeps the connection reusable, the start of Envoy's next upstream request is consumed as the prior request's body, and the remainder is parsed by the origin as a separate, attacker-controlled request. This was demonstrated as a route-bypass: a directly denied /pwn was served to a second downstream stream as a backend-parsed GET /pwn, with no public exploit identified at time of analysis and no CISA KEV listing.
Remote denial of service in Envoy proxy allows attackers to crash the process by resolving a DNS name exactly 255 octets long through a configured UDP DNS filter. An off-by-one runtime precondition assumes query names are strictly less than 255 octets, contradicting RFC 1035 which permits names of up to 255 octets, so a maximally-long name that resolves successfully triggers abnormal process termination. There is no public exploit identified at time of analysis, EPSS is low (0.37%), and CISA SSVC rates exploitation as none with only partial technical impact.
Denial of service in Envoy proxy (versions 1.23.0 through 1.35.10, 1.36.6, 1.37.2, and 1.38.0) allows remote unauthenticated attackers to crash the proxy by sending a specially crafted, highly compressed zstd payload that triggers massive memory allocation in the ZstdDecompressorImpl, leading to Out-Of-Memory kills. The flaw is a decompression-bomb (data amplification) issue that only manifests when zstd decompression is enabled. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; the high CVSS reflects availability impact only (A:H, no confidentiality or integrity loss).
Denial of service in Envoy proxy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 allows remote unauthenticated attackers to crash the proxy by submitting deeply nested JSON (on the order of 100,000 levels). When the resulting JSON Object is torn down, its recursive destructor exhausts the thread stack, causing a stack overflow and process termination. There is no public exploit identified at time of analysis and the issue impacts availability only; the CVSS 3.1 base score is 7.5.
Denial of service in Envoy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 allows unauthenticated remote clients to trigger excessive memory consumption via crafted HTTP/2 requests, potentially causing OOM termination of the Envoy process. The flaw stems from cookie header bytes bypassing request header size validation combined with HPACK limits being enforced only on encoded bytes. No public exploit identified at time of analysis, but the network-reachable, no-auth attack profile makes it a credible availability threat for edge proxies.
Envoy's RBAC filter improperly concatenates duplicate HTTP headers into comma-separated strings instead of validating each value individually, allowing attackers to bypass "Deny" access control policies through header manipulation. This vulnerability affects Envoy versions prior to 1.34.13, 1.35.8, 1.36.5, and 1.37.1, and public exploit code exists. Patches are available for all affected versions.
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resources by rapidly opening and immediately canceling (RST_STREAM) large numbers of streams over a single connection, a technique dubbed the 'Rapid Reset' attack. The flaw is confirmed actively exploited (CISA KEV) following large-scale weaponization observed August through October 2023, with publicly available exploit code and an EPSS score of 94.45% placing it in the 100th percentile for likelihood of exploitation. Virtually every major HTTP/2 stack - including nghttp2, Netty, Envoy, and Eclipse Jetty - is affected.
Path-confusion access-control bypass in Envoy Proxy before versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1 allows remote, unauthenticated clients to reach resources that a path-based Envoy policy (path-based route selection or path-based authorization) intended to protect. Envoy matches the raw request path, while servlet backends such as Apache Tomcat strip semicolon matrix parameters from each path segment before resolving the resource, so a request like /admin;x=1 is matched by Envoy against an unprotected fallback route while the backend still serves the protected resource; Envoy's legacy ignore_path_parameters_in_path_matching option only truncates at the first semicolon and does not reproduce per-segment backend behavior. Exploitation is conditional (it requires both a path-based Envoy decision and a backend that strips semicolon parameters per segment) and the assessed impact is limited to Low confidentiality with no integrity or availability effect; no public exploit identified at time of analysis.
Path confusion in Envoy Proxy lets remote, unauthenticated clients bypass path-based authorization and routing policy by attaching semicolon parameters to dot and dotdot segments - a request such as /user/..;foo=bar/admin is not canonicalized to /admin even when path normalization is enabled, so a client can present one path to Envoy's policy engine and a different effective path to the upstream. The security consequence materializes only when Envoy itself makes a path-based RBAC or routing decision on the uncollapsed value, or when a downstream/upstream collapses the segment per RFC 3986 while Envoy does not; without such a mismatch the exposure is limited to low-confidentiality impact. The issue is fixed in Envoy 1.36.10, 1.37.6, 1.38.4, and 1.39.1; no public exploit code was identified at time of analysis and no CISA KEV or EPSS signal was provided. Note that the attached tag reads 'Authentication Bypass', but the assessed impact is a moderate-severity access-control (path confusion) bypass, not an authentication bypass.
Envoy Proxy worker processes can be crashed remotely by routine traffic when an upstream cluster is configured with ALPN-based auto protocol selection and HTTP/3 enabled, because ProdClusterManagerFactory::allocateConnPool dereferences transport-socket options without a null check when selecting an HTTP/3 connection pool. The affected code paths are those where the LoadBalancerContext supplies no transport-socket options - synthetic, mirror, health-check and async-client (internal) requests - so any HTTP/3-enabled auto_config deployment that routes through one of these contexts is exposed to a repeatable availability loss; no authentication, user interaction, or unusual client behavior is required (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H, 5.9, CWE-476). The issue is not reported as actively exploited and no public exploit code has been identified at time of analysis, and the practical impact is gated by the requirement for the specific auto_config-plus-HTTP/3 upstream configuration. Vendor fixes ship in Envoy 1.36.10, 1.37.6, 1.38.4 and 1.39.1.
Process termination in Envoy Proxy affects versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 when a scoped IPv6 address (for example fe80::1%1) reaches either the ORIGINAL_DST transparent-proxy cluster path or a QUIC client connection undergoing port migration; the address is re-serialized with its percent scope suffix and then handed to inet_pton, which cannot parse it, so an EnvoyException is thrown and the process aborts. The assessed vector is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (5.3), meaning an unauthenticated remote condition can be reached without user interaction but only under narrow, topology-dependent prerequisites, and impact is availability-only - there is no confidentiality or integrity loss. This is a genuine but conditional availability-only issue: it is not a default configuration (transparent proxying with ORIGINAL_DST, or QUIC, must be in use and the destination must actually be a scoped/link-local IPv6 address), no public exploit identified at time of analysis, no CISA KEV listing, and no EPSS signal was supplied with the data.
Use-after-free in Envoy's HTTP external-authorization (ext_authz) client crashes the proxy process with a SIGSEGV-class fault when the authorization response is processed after the request callback owner has already been destroyed. Envoy deployments running releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 that have enabled the HTTP ext_authz filter are affected; per the CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H, 5.9) an unauthenticated remote client needs only to send traffic that the external authorization service rejects, with triggering gated on a request-rejection-then-stale-callback timing window rather than a single deterministic request. Exploitation is not confirmed actively exploited (no CISA KEV entry) and no public exploit code has been identified at time of analysis; impact is availability-only, with no data exposure or code execution demonstrated.
Use-after-free in Envoy's HTTP OAuth2 filter (envoy.filters.http.oauth2) across versions 1.37.0-1.37.4 and 1.38.0-1.38.2 enables unauthenticated remote attackers to crash Envoy worker threads by racing a connection teardown against an in-flight async token exchange. When a downstream client disconnects while the filter is awaiting an async OAuth2 token response, the late AsyncClient callback invokes StreamDecoderFilterCallbacks on an already-freed object, producing undefined behavior and worker crashes. The reporter explicitly disclaims RCE - confirmed impact is availability loss (DoS); allocator-dependent memory corruption effects beyond crash are theoretically possible but not demonstrated. No public exploit or CISA KEV listing identified at time of analysis.
Use-After-Free crash in Envoy's ext_authz HTTP filter allows remote unauthenticated attackers to trigger a segmentation fault and process crash by rapidly establishing and tearing down downstream connections when per-route authorization overrides are configured. Affected are Envoy versions 1.36.0-1.36.8, 1.37.0-1.37.4, and 1.38.0-1.38.2. No public exploit code has been identified and this vulnerability is not listed in the CISA KEV catalog, though the race condition exploitability is constrained by requiring specific ext_authz per-route override configuration.
PROXY Protocol v2 TLV overflow in Envoy Proxy versions 1.34.0 through the pre-fix series allows an operator-level attacker on an adjacent network to smuggle extraneous bytes into upstream requests. Envoy's header generator writes TLV content exceeding the protocol-mandated 65535-byte maximum without adjusting the length field, creating a header where declared length and actual byte count diverge - a textbook CWE-130 length-parameter inconsistency. No public exploit code has been identified and this vulnerability does not appear in the CISA KEV catalog; risk is constrained by the high-privilege and adjacent-network prerequisites reflected in the CVSS 4.8 medium score.
Envoy proxy's External Processing (ext_proc) filter crashes with a use-after-free when an ext_proc gRPC server sends a single batched gRPC message containing multiple specially crafted ProcessingResponse objects. Affected versions span 1.34.0 through pre-fix releases across four maintained branches; fixed releases are 1.35.13, 1.36.9, 1.37.5, and 1.38.3. With CVSS PR:L, exploitation requires control of or compromise of the ext_proc gRPC server endpoint, limiting the realistic attacker population but making this a high-priority patch for any deployment running ext_proc. No public exploit code and no CISA KEV listing exist at time of analysis.
Certificate SAN validation in Envoy Proxy is bypassed when an attacker-controlled upstream serves a TLS certificate containing an embedded NUL byte in the dNSName Subject Alternative Name field. Envoy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 are affected, allowing an attacker who controls or can impersonate an upstream TLS endpoint to pass Envoy's configured SAN match check with a fraudulent certificate and intercept proxied traffic. No public exploit code has been identified at time of analysis, and this vulnerability is not listed in the CISA KEV catalog.
The OAuth2 HTTP filter in Envoy Proxy prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 implements AES-256-CBC encryption for the PKCE CodeVerifier cookie without any authentication tag, creating a classic padding oracle through differential HTTP responses on the /callback endpoint. An attacker who obtains the victim's encrypted CodeVerifier cookie and a stolen authorization code can recover the plaintext PKCE code_verifier in approximately 6,200 crafted requests (~100 seconds), then complete the OAuth token exchange to hijack the victim's access token. No public exploit code or CISA KEV listing has been identified at time of analysis; vendor-confirmed patches are available in all four current release branches.
Envoy proxy versions prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13 can be crashed by an authenticated attacker through improper state cleanup in the rate limit filter when both request and response phase limiting are enabled. When a response phase rate limit request fails, the gRPC client reuses stale internal state from the prior request phase, leading to a use-after-free condition that crashes the proxy. An attacker with network access and valid credentials can exploit this to cause a denial of service against Envoy instances.
Envoy proxy versions before 1.37.1, 1.36.5, 1.35.8, and 1.34.13 contain a use-after-free vulnerability in the HTTP connection manager that allows attackers to trigger denial of service by sending data frames on streams after they have been reset. Public exploit code exists for this vulnerability, and no patch is currently available. The flaw enables filter callbacks to execute on logically cleaned-up streams, potentially causing service disruption or state corruption.
Envoy proxy versions prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13 crash when processing scoped IPv6 addresses through the Utility::getAddressWithPort function, which is invoked by the original_src and dns filters in the data plane. This denial of service vulnerability can be triggered remotely without authentication, and public exploit code exists. No patch is currently available for affected deployments.
Envoy is a high-performance edge/middle/service proxy. [CVSS 5.3 MEDIUM]
Identity impersonation in Envoy Proxy (1.33.12 and earlier, 1.34.0-1.34.10, 1.35.0-1.35.6, and 1.36.0-1.36.2) allows a client to be accepted under a different identity when Envoy is configured with require_client_certificate: true and an exact match_typed_subject_alt_names rule against an OTHERNAME SAN. Specifically, a certificate whose OTHERNAME value is encoded as BMPSTRING or UNIVERSALSTRING and carries an embedded null byte (for example 'victim\0evil') is truncated at the null during UTF-8 conversion and therefore matches an exact rule for 'victim', granting the attacker the access rights of that identity. Publicly available exploit code exists and the vendor has released patches, but EPSS is 0.00% and exploitation is gated on the attacker first obtaining a CA-signed certificate from a CA that Envoy trusts, so this is a precondition-heavy issue rather than a mass-exploitable one. Note authentication requirements: the CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N, indicating the attacker must already hold valid credentials (a trusted client certificate).
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, when Envoy is configured in TCP proxy mode to handle CONNECT requests, it accepts client data before issuing a 2xx response and forwards that data to the upstream TCP connection. If a forwarding proxy upstream from Envoy then responds with a non-2xx status, this can cause a de-synchronized CONNECT tunnel state. By default Envoy continues to allow early CONNECT data to avoid disrupting existing deployments. The envoy.reloadable_features.reject_early_connect_data runtime flag can be set to reject CONNECT requests that send data before a 2xx response when intermediaries upstream from Envoy may reject establishment of a CONNECT tunnel.
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, Envoy crashes when JWT authentication is configured with the remote JWKS fetching, allow_missing_or_failed is enabled, multiple JWT tokens are present in the request headers and the JWKS fetch fails. This is caused by a re-entry bug in the JwksFetcherImpl. When the first token's JWKS fetch fails, onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object. The original callback's reset() then clears the second fetch's state (receiver_ and request_) which causes a crash when the async HTTP response arrives.
Denial of service in Envoy Proxy's Lua HTTP filter occurs when a response-phase Lua script rewrites a response body to exceed the configured per_connection_buffer_limit_bytes (default 1MB), forcing a local reply that overrides original response headers and leaves dangling references, resulting in a use-after-free crash. Only deployments that use a Lua HTTP filter to rewrite response bodies are affected; stock Envoy configurations without such a filter are not vulnerable. No public exploit code or active exploitation has been identified at time of analysis, and EPSS is low at 0.42% (34th percentile).
Denial of service in Envoy Proxy affects all builds prior to 1.36.1, 1.35.5, 1.34.9, and 1.33.10, where remote, unauthenticated attackers can crash a TCP connection pool when large requests or responses overlap with a connection being closed while upstream data is still arriving. The fault is a null pointer dereference (CWE-476) in Envoy's flow-control/buffer watermark callback path, reachable in TCP proxy and mixed HTTP/1 and HTTP/2 (ALPN-negotiated) deployments; plain single-protocol HTTP setups are not indicated as affected. Impact is availability-only - no confidentiality or integrity loss and no code execution - and there is no public exploit identified at time of analysis (EPSS roughly 0.46%, 38th percentile). Because the crash depends on a timing-sensitive 'closing connection plus in-flight upstream data plus large payload' state, our independent assessment rates attack complexity as High even though the vendor's CVSS 4.0 vector (base 6.6) lists AC:L.
Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native edge/middle/service proxy. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native, open source edge and service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native, open-source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native high-performance proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native high-performance proxy. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Missing Authentication for Critical Function vulnerability could allow attackers to access critical functionality without authentication.
Envoy is a cloud-native high-performance proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance proxy. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Pomerium is an open source identity-aware access proxy. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Pomerium is an open source identity-aware access proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Path-based RBAC authorization bypass in Envoy Proxy lets an unauthenticated remote client reach protected backends such as /admin by appending a semicolon path parameter (e.g. /admin;x), because the router strips that suffix before route matching while the RBAC url_path matcher evaluates the untouched raw path. Exploitation is tightly gated rather than default: it requires a route configured with ignore_path_parameters_in_path_matching, a path-based RBAC rule (PathMatcher or UriTemplateMatcher) guarding the protected path, and a crafted request that still selects the protected route after stripping. All releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected; the vendor has published fixed releases, and no public exploit code or confirmed active exploitation (CISA KEV) was identified at time of analysis.
Stored cross-site scripting in Envoy Proxy's admin statistics page lets an attacker run script in the admin interface's origin: the /stats?format=html endpoint (StatsHtmlRender) sanitizes statistic values but emits statistic names raw, so a data-plane component that folds attacker-supplied request path segments into dynamic stat names - notably grpc_stats with stats_for_all_methods enabled - can persist a script-bearing name that fires when an operator opens the page in a browser. Every release before 1.36.10, 1.37.6, 1.38.4, and 1.39.1 is affected; the independently assessed vector is CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N (7.4), i.e. unauthenticated remote influence over the injected text but multiple gating prerequisites plus required operator interaction, with impact scoped to the admin origin where privileged same-origin requests can then be issued. No public exploit code has been identified at time of analysis and the CVE is not listed in CISA KEV; exploitation is realistic only where the admin HTML endpoint is browser-reachable and a dynamic-stat-generating component is enabled.
Envoy Proxy releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 can be crashed by a remote, unauthenticated attacker through its HTTP/3 datagram and Capsule Protocol handling (prerequisites: PR:N, no user interaction). When a request enters a stream-recreation path such as an internal redirect, the HttpDatagramHandler keeps a cached pointer to the original RequestDecoder; a subsequent HTTP/3 datagram invokes decodeData through that freed decoder, producing invalid virtual dispatch and process termination (CWE-416 use-after-free, CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H). Exploitation is gated on a non-default configuration - HTTP/3 (QUIC) downstream plus Capsule Protocol enabled, e.g. MASQUE connect-udp tunneling - combined with an internal-redirect route and precise frame sequencing; no public exploit code or CISA KEV entry was identified at time of analysis.
Unauthenticated remote attackers can exhaust memory and trigger an out-of-memory kill of Envoy Proxy by sending HTTP/2 requests that include a large Host header alongside an existing :authority pseudo-header, since the discarded Host value is copied but never charged against header size or count limits, and HPACK dynamic-table indexing lets an attacker repeatedly reference that large value across a bounded number of streams. All Envoy releases before 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected, including both the nghttp2 and oghttp2 HTTP/2 codec implementations, and the flaw is reachable on any listener that terminates HTTP/2 with no authentication or user interaction required (CVSS 3.1 base 7.5, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, CWE-401). No public exploit code and no confirmed active exploitation have been identified at time of analysis, but the low complexity and lack of prerequisites make this a practical availability risk for internet-facing edge proxies; note the supplied "Authentication Bypass" tag is misleading - the impact is availability-only, with no confidentiality or integrity loss.
Unauthenticated remote clients can crash Envoy Proxy by sending a path-less CONNECT request when the ext_authz HTTP filter is configured to apply query_parameters_to_set or query_parameters_to_remove mutations and the external authorization service returns such a mutation. The crash is a null-pointer dereference in the ext_authz filter's Filter::onComplete path, producing a denial of service (CVSS 7.5, A:H) against the affected proxy process; impact is limited to availability, with no confidentiality or integrity loss. Exploitation is gated by two non-default configuration prerequisites - accepting path-less CONNECT and enabling ext_authz query-parameter mutation - and no public exploit code has been identified at time of analysis.
Denial of service in Envoy Proxy releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, where the optional oghttp2 upstream HTTP/2 codec accepts a response trailer HEADERS frame that lacks the END_STREAM flag, causing Envoy to complete and deferred-delete the ActiveRequest while oghttp2 keeps the stream open. The resulting dangling reference in ClientStreamImpl (response_decoder_) can be dereferenced by a subsequent frame on that stream, freeing-then-using memory and crashing the Envoy process (CWE-20, CVSS 3.1 7.5, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - assessed independently at AC:H). Exploitation is remote and unauthenticated once preconditions hold, but it is limited to non-default configurations: the oghttp2 upstream codec must be explicitly enabled, the malformed trailers must be emitted by the upstream server Envoy proxies to (an attacker-controlled or compromised upstream, or injected frames on that connection), and the default nghttp2 codec rejects the malformed trailers outright. Vendor patches are available (1.36.10, 1.37.6, 1.38.4, 1.39.1); no public exploit code was identified and the issue is not in CISA KEV at time of analysis.
An access-control bypass in Envoy Proxy (all versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1) allows unauthenticated remote clients to reach routes that HTTP RBAC policies were configured to deny, resulting in disclosure of protected content. The flaw only materializes when a NEGATIVE (DENY) policy uses a safe_regex matcher against header values and a byte-oriented route matcher independently reads the raw header bytes; positive ALLOW regexes fail closed and exact, prefix, suffix, and contains matchers are unaffected. No public exploit code has been identified at time of analysis, and the vendor has released fixed versions, so real-world risk is driven almost entirely by whether a deployment uses that specific safe_regex-in-negative-policy configuration.
Request smuggling in Envoy Proxy allows an unauthenticated HTTP/2 client to embed a complete HTTP/1.1 request inside the data payload of an extended CONNECT (a generic, non-WebSocket HTTP upgrade) so that Envoy forwards that payload upstream before the upstream has accepted the upgrade, writes it unframed to a keep-alive HTTP/1.1 upstream, and returns the upstream socket to the shared pool with a smuggled response still queued - meaning a different, unrelated downstream client can subsequently be served the attacker's response. Every Envoy release prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 is affected, but exploitation is configuration-dependent: the listener must proxy a generic non-WebSocket upgrade to an HTTP/1.1 upstream with backend keep-alive enabled, shared (non-per-downstream) connection pools, and max_requests_per_connection not set to 1; WebSocket upgrades, plain CONNECT, disabled backend keep-alive, per-downstream pools, and max_requests_per_connection=1 are explicitly out of scope for the demonstrated path. No public exploit code has been identified at time of analysis, and this CVE is not listed in CISA KEV.
Denial of service in Envoy proxy versions 1.37.0 through 1.37.4 and 1.38.x before 1.38.3 lets remote attackers crash the proxy by sending a request that omits the Host header when access logging is configured with the %REQUESTED_SERVER_NAME(X:Y)% operator using host-related options (e.g. HOST_FIRST, SNI_FIRST). The missing header triggers a null pointer dereference (CWE-476), taking down the data-plane proxy and any traffic flowing through it. No public exploit identified at time of analysis and the issue is not in CISA KEV.
Heap buffer overflow in Envoy's TcpStatsdSink component (versions 1.34.0 through pre-fix releases) allows unauthenticated remote attackers to crash the Envoy process or potentially achieve remote code execution by submitting HTTP or gRPC requests with request paths exceeding 16KiB, provided a specific non-default dual-filter configuration is present. The root flaw is an incorrect buffer rotation in the thread-local metric flusher that allocates a new 16KiB slice but continues writing beyond its boundary via unchecked memcpy operations. No public exploit has been identified at time of analysis, though vendor-confirmed patches are available across all affected release branches (1.35.13, 1.36.9, 1.37.5, 1.38.3).
The envoy.filters.http.grpc_stats HTTP filter in Envoy versions 1.26.0 through the pre-fix releases crashes with a null pointer dereference when a Connect protocol request (Content-Type: application/connect+proto or application/connect+json) is routed to a direct_response route, terminating the Envoy process entirely. The vendor description states a single unauthenticated HTTP request is sufficient to trigger the crash, giving any network-reachable attacker a trivial one-packet denial of service against affected deployments. No confirmed active exploitation (absent from CISA KEV) and no public exploit code has been identified at time of analysis, but the trivial trigger condition makes this high practical risk for any deployment with both preconditions present.
Null pointer dereference in Envoy's router filter crashes the entire proxy process, terminating all active connections, when body-less non-GET/HEAD requests (POST, PUT, DELETE, PATCH) encounter an upstream HTTP 303 response on a route configured with internal redirect policy. Affected versions span 1.18.0 through the fixes released in branches 1.35.13, 1.36.9, 1.37.5, and 1.38.3. An unauthenticated remote attacker who can influence upstream response codes or reach a vulnerable route configuration can cause complete denial of service; no public exploit identified at time of analysis and no CISA KEV listing.
HTTP request smuggling in Envoy proxy (versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1) lets remote attackers desynchronize HTTP/1 upstream connections by sending an HTTP/3 downstream request that is transport-complete (HEADERS with FIN) yet declares a nonzero Content-Length, leaving the translated HTTP/1 request with unresolved body debt. When the HTTP/1 origin replies before reading the body and keeps the connection reusable, the start of Envoy's next upstream request is consumed as the prior request's body, and the remainder is parsed by the origin as a separate, attacker-controlled request. This was demonstrated as a route-bypass: a directly denied /pwn was served to a second downstream stream as a backend-parsed GET /pwn, with no public exploit identified at time of analysis and no CISA KEV listing.
Remote denial of service in Envoy proxy allows attackers to crash the process by resolving a DNS name exactly 255 octets long through a configured UDP DNS filter. An off-by-one runtime precondition assumes query names are strictly less than 255 octets, contradicting RFC 1035 which permits names of up to 255 octets, so a maximally-long name that resolves successfully triggers abnormal process termination. There is no public exploit identified at time of analysis, EPSS is low (0.37%), and CISA SSVC rates exploitation as none with only partial technical impact.
Denial of service in Envoy proxy (versions 1.23.0 through 1.35.10, 1.36.6, 1.37.2, and 1.38.0) allows remote unauthenticated attackers to crash the proxy by sending a specially crafted, highly compressed zstd payload that triggers massive memory allocation in the ZstdDecompressorImpl, leading to Out-Of-Memory kills. The flaw is a decompression-bomb (data amplification) issue that only manifests when zstd decompression is enabled. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; the high CVSS reflects availability impact only (A:H, no confidentiality or integrity loss).
Denial of service in Envoy proxy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 allows remote unauthenticated attackers to crash the proxy by submitting deeply nested JSON (on the order of 100,000 levels). When the resulting JSON Object is torn down, its recursive destructor exhausts the thread stack, causing a stack overflow and process termination. There is no public exploit identified at time of analysis and the issue impacts availability only; the CVSS 3.1 base score is 7.5.
Denial of service in Envoy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 allows unauthenticated remote clients to trigger excessive memory consumption via crafted HTTP/2 requests, potentially causing OOM termination of the Envoy process. The flaw stems from cookie header bytes bypassing request header size validation combined with HPACK limits being enforced only on encoded bytes. No public exploit identified at time of analysis, but the network-reachable, no-auth attack profile makes it a credible availability threat for edge proxies.
Envoy's RBAC filter improperly concatenates duplicate HTTP headers into comma-separated strings instead of validating each value individually, allowing attackers to bypass "Deny" access control policies through header manipulation. This vulnerability affects Envoy versions prior to 1.34.13, 1.35.8, 1.36.5, and 1.37.1, and public exploit code exists. Patches are available for all affected versions.
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resources by rapidly opening and immediately canceling (RST_STREAM) large numbers of streams over a single connection, a technique dubbed the 'Rapid Reset' attack. The flaw is confirmed actively exploited (CISA KEV) following large-scale weaponization observed August through October 2023, with publicly available exploit code and an EPSS score of 94.45% placing it in the 100th percentile for likelihood of exploitation. Virtually every major HTTP/2 stack - including nghttp2, Netty, Envoy, and Eclipse Jetty - is affected.
Path-confusion access-control bypass in Envoy Proxy before versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1 allows remote, unauthenticated clients to reach resources that a path-based Envoy policy (path-based route selection or path-based authorization) intended to protect. Envoy matches the raw request path, while servlet backends such as Apache Tomcat strip semicolon matrix parameters from each path segment before resolving the resource, so a request like /admin;x=1 is matched by Envoy against an unprotected fallback route while the backend still serves the protected resource; Envoy's legacy ignore_path_parameters_in_path_matching option only truncates at the first semicolon and does not reproduce per-segment backend behavior. Exploitation is conditional (it requires both a path-based Envoy decision and a backend that strips semicolon parameters per segment) and the assessed impact is limited to Low confidentiality with no integrity or availability effect; no public exploit identified at time of analysis.
Path confusion in Envoy Proxy lets remote, unauthenticated clients bypass path-based authorization and routing policy by attaching semicolon parameters to dot and dotdot segments - a request such as /user/..;foo=bar/admin is not canonicalized to /admin even when path normalization is enabled, so a client can present one path to Envoy's policy engine and a different effective path to the upstream. The security consequence materializes only when Envoy itself makes a path-based RBAC or routing decision on the uncollapsed value, or when a downstream/upstream collapses the segment per RFC 3986 while Envoy does not; without such a mismatch the exposure is limited to low-confidentiality impact. The issue is fixed in Envoy 1.36.10, 1.37.6, 1.38.4, and 1.39.1; no public exploit code was identified at time of analysis and no CISA KEV or EPSS signal was provided. Note that the attached tag reads 'Authentication Bypass', but the assessed impact is a moderate-severity access-control (path confusion) bypass, not an authentication bypass.
Envoy Proxy worker processes can be crashed remotely by routine traffic when an upstream cluster is configured with ALPN-based auto protocol selection and HTTP/3 enabled, because ProdClusterManagerFactory::allocateConnPool dereferences transport-socket options without a null check when selecting an HTTP/3 connection pool. The affected code paths are those where the LoadBalancerContext supplies no transport-socket options - synthetic, mirror, health-check and async-client (internal) requests - so any HTTP/3-enabled auto_config deployment that routes through one of these contexts is exposed to a repeatable availability loss; no authentication, user interaction, or unusual client behavior is required (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H, 5.9, CWE-476). The issue is not reported as actively exploited and no public exploit code has been identified at time of analysis, and the practical impact is gated by the requirement for the specific auto_config-plus-HTTP/3 upstream configuration. Vendor fixes ship in Envoy 1.36.10, 1.37.6, 1.38.4 and 1.39.1.
Process termination in Envoy Proxy affects versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 when a scoped IPv6 address (for example fe80::1%1) reaches either the ORIGINAL_DST transparent-proxy cluster path or a QUIC client connection undergoing port migration; the address is re-serialized with its percent scope suffix and then handed to inet_pton, which cannot parse it, so an EnvoyException is thrown and the process aborts. The assessed vector is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (5.3), meaning an unauthenticated remote condition can be reached without user interaction but only under narrow, topology-dependent prerequisites, and impact is availability-only - there is no confidentiality or integrity loss. This is a genuine but conditional availability-only issue: it is not a default configuration (transparent proxying with ORIGINAL_DST, or QUIC, must be in use and the destination must actually be a scoped/link-local IPv6 address), no public exploit identified at time of analysis, no CISA KEV listing, and no EPSS signal was supplied with the data.
Use-after-free in Envoy's HTTP external-authorization (ext_authz) client crashes the proxy process with a SIGSEGV-class fault when the authorization response is processed after the request callback owner has already been destroyed. Envoy deployments running releases prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 that have enabled the HTTP ext_authz filter are affected; per the CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H, 5.9) an unauthenticated remote client needs only to send traffic that the external authorization service rejects, with triggering gated on a request-rejection-then-stale-callback timing window rather than a single deterministic request. Exploitation is not confirmed actively exploited (no CISA KEV entry) and no public exploit code has been identified at time of analysis; impact is availability-only, with no data exposure or code execution demonstrated.
Use-after-free in Envoy's HTTP OAuth2 filter (envoy.filters.http.oauth2) across versions 1.37.0-1.37.4 and 1.38.0-1.38.2 enables unauthenticated remote attackers to crash Envoy worker threads by racing a connection teardown against an in-flight async token exchange. When a downstream client disconnects while the filter is awaiting an async OAuth2 token response, the late AsyncClient callback invokes StreamDecoderFilterCallbacks on an already-freed object, producing undefined behavior and worker crashes. The reporter explicitly disclaims RCE - confirmed impact is availability loss (DoS); allocator-dependent memory corruption effects beyond crash are theoretically possible but not demonstrated. No public exploit or CISA KEV listing identified at time of analysis.
Use-After-Free crash in Envoy's ext_authz HTTP filter allows remote unauthenticated attackers to trigger a segmentation fault and process crash by rapidly establishing and tearing down downstream connections when per-route authorization overrides are configured. Affected are Envoy versions 1.36.0-1.36.8, 1.37.0-1.37.4, and 1.38.0-1.38.2. No public exploit code has been identified and this vulnerability is not listed in the CISA KEV catalog, though the race condition exploitability is constrained by requiring specific ext_authz per-route override configuration.
PROXY Protocol v2 TLV overflow in Envoy Proxy versions 1.34.0 through the pre-fix series allows an operator-level attacker on an adjacent network to smuggle extraneous bytes into upstream requests. Envoy's header generator writes TLV content exceeding the protocol-mandated 65535-byte maximum without adjusting the length field, creating a header where declared length and actual byte count diverge - a textbook CWE-130 length-parameter inconsistency. No public exploit code has been identified and this vulnerability does not appear in the CISA KEV catalog; risk is constrained by the high-privilege and adjacent-network prerequisites reflected in the CVSS 4.8 medium score.
Envoy proxy's External Processing (ext_proc) filter crashes with a use-after-free when an ext_proc gRPC server sends a single batched gRPC message containing multiple specially crafted ProcessingResponse objects. Affected versions span 1.34.0 through pre-fix releases across four maintained branches; fixed releases are 1.35.13, 1.36.9, 1.37.5, and 1.38.3. With CVSS PR:L, exploitation requires control of or compromise of the ext_proc gRPC server endpoint, limiting the realistic attacker population but making this a high-priority patch for any deployment running ext_proc. No public exploit code and no CISA KEV listing exist at time of analysis.
Certificate SAN validation in Envoy Proxy is bypassed when an attacker-controlled upstream serves a TLS certificate containing an embedded NUL byte in the dNSName Subject Alternative Name field. Envoy versions prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1 are affected, allowing an attacker who controls or can impersonate an upstream TLS endpoint to pass Envoy's configured SAN match check with a fraudulent certificate and intercept proxied traffic. No public exploit code has been identified at time of analysis, and this vulnerability is not listed in the CISA KEV catalog.
The OAuth2 HTTP filter in Envoy Proxy prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 implements AES-256-CBC encryption for the PKCE CodeVerifier cookie without any authentication tag, creating a classic padding oracle through differential HTTP responses on the /callback endpoint. An attacker who obtains the victim's encrypted CodeVerifier cookie and a stolen authorization code can recover the plaintext PKCE code_verifier in approximately 6,200 crafted requests (~100 seconds), then complete the OAuth token exchange to hijack the victim's access token. No public exploit code or CISA KEV listing has been identified at time of analysis; vendor-confirmed patches are available in all four current release branches.
Envoy proxy versions prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13 can be crashed by an authenticated attacker through improper state cleanup in the rate limit filter when both request and response phase limiting are enabled. When a response phase rate limit request fails, the gRPC client reuses stale internal state from the prior request phase, leading to a use-after-free condition that crashes the proxy. An attacker with network access and valid credentials can exploit this to cause a denial of service against Envoy instances.
Envoy proxy versions before 1.37.1, 1.36.5, 1.35.8, and 1.34.13 contain a use-after-free vulnerability in the HTTP connection manager that allows attackers to trigger denial of service by sending data frames on streams after they have been reset. Public exploit code exists for this vulnerability, and no patch is currently available. The flaw enables filter callbacks to execute on logically cleaned-up streams, potentially causing service disruption or state corruption.
Envoy proxy versions prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13 crash when processing scoped IPv6 addresses through the Utility::getAddressWithPort function, which is invoked by the original_src and dns filters in the data plane. This denial of service vulnerability can be triggered remotely without authentication, and public exploit code exists. No patch is currently available for affected deployments.
Envoy is a high-performance edge/middle/service proxy. [CVSS 5.3 MEDIUM]
Identity impersonation in Envoy Proxy (1.33.12 and earlier, 1.34.0-1.34.10, 1.35.0-1.35.6, and 1.36.0-1.36.2) allows a client to be accepted under a different identity when Envoy is configured with require_client_certificate: true and an exact match_typed_subject_alt_names rule against an OTHERNAME SAN. Specifically, a certificate whose OTHERNAME value is encoded as BMPSTRING or UNIVERSALSTRING and carries an embedded null byte (for example 'victim\0evil') is truncated at the null during UTF-8 conversion and therefore matches an exact rule for 'victim', granting the attacker the access rights of that identity. Publicly available exploit code exists and the vendor has released patches, but EPSS is 0.00% and exploitation is gated on the attacker first obtaining a CA-signed certificate from a CA that Envoy trusts, so this is a precondition-heavy issue rather than a mass-exploitable one. Note authentication requirements: the CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N, indicating the attacker must already hold valid credentials (a trusted client certificate).
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, when Envoy is configured in TCP proxy mode to handle CONNECT requests, it accepts client data before issuing a 2xx response and forwards that data to the upstream TCP connection. If a forwarding proxy upstream from Envoy then responds with a non-2xx status, this can cause a de-synchronized CONNECT tunnel state. By default Envoy continues to allow early CONNECT data to avoid disrupting existing deployments. The envoy.reloadable_features.reject_early_connect_data runtime flag can be set to reject CONNECT requests that send data before a 2xx response when intermediaries upstream from Envoy may reject establishment of a CONNECT tunnel.
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, Envoy crashes when JWT authentication is configured with the remote JWKS fetching, allow_missing_or_failed is enabled, multiple JWT tokens are present in the request headers and the JWKS fetch fails. This is caused by a re-entry bug in the JwksFetcherImpl. When the first token's JWKS fetch fails, onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object. The original callback's reset() then clears the second fetch's state (receiver_ and request_) which causes a crash when the async HTTP response arrives.
Denial of service in Envoy Proxy's Lua HTTP filter occurs when a response-phase Lua script rewrites a response body to exceed the configured per_connection_buffer_limit_bytes (default 1MB), forcing a local reply that overrides original response headers and leaves dangling references, resulting in a use-after-free crash. Only deployments that use a Lua HTTP filter to rewrite response bodies are affected; stock Envoy configurations without such a filter are not vulnerable. No public exploit code or active exploitation has been identified at time of analysis, and EPSS is low at 0.42% (34th percentile).
Denial of service in Envoy Proxy affects all builds prior to 1.36.1, 1.35.5, 1.34.9, and 1.33.10, where remote, unauthenticated attackers can crash a TCP connection pool when large requests or responses overlap with a connection being closed while upstream data is still arriving. The fault is a null pointer dereference (CWE-476) in Envoy's flow-control/buffer watermark callback path, reachable in TCP proxy and mixed HTTP/1 and HTTP/2 (ALPN-negotiated) deployments; plain single-protocol HTTP setups are not indicated as affected. Impact is availability-only - no confidentiality or integrity loss and no code execution - and there is no public exploit identified at time of analysis (EPSS roughly 0.46%, 38th percentile). Because the crash depends on a timing-sensitive 'closing connection plus in-flight upstream data plus large payload' state, our independent assessment rates attack complexity as High even though the vendor's CVSS 4.0 vector (base 6.6) lists AC:L.
Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native edge/middle/service proxy. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native, open source edge and service proxy. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native, open source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native, open-source edge and service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a high-performance edge/middle/service proxy. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
Envoy is a high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is an open source edge and service proxy designed for cloud-native applications. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Envoy is a cloud-native high-performance proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is a cloud-native high-performance edge/middle/service proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
Envoy is a cloud-native high-performance proxy. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Missing Authentication for Critical Function vulnerability could allow attackers to access critical functionality without authentication.
Envoy is a cloud-native high-performance proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Envoy is a cloud-native high-performance proxy. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Envoy is an open source edge and service proxy, designed for cloud-native applications. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Pomerium is an open source identity-aware access proxy. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Pomerium is an open source identity-aware access proxy. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.