Varnish Cache
Monthly
Varnish Cache 9.0.0 crashes (denial of service) when a remote client exploits timing between timeout_linger and timeout_idle to trigger HTTP/1 request pipelining that causes a workspace overflow in the refactored HTTP/2 architecture. The vulnerability stems from incomplete code path handling during workspace rollback in the recent non-blocking port, allowing prefetched data to exceed workspace_client boundaries and panic the daemon. Vendor-released patch: version 9.0.1. No public exploit code identified at time of analysis, but the attack requires only network access and careful timing, making real-world exploitation feasible for sophisticated attackers.
Denial of service via workspace overflow in Varnish Cache 9 before 9.0.1 and Varnish Enterprise before 6.0.16r11 allows unauthenticated remote attackers to trigger daemon panic through HTTP/2 session upgrade with specific amounts of prefetched data. The vulnerability exploits improper buffer allocation during HTTP/1 to HTTP/2 transport upgrade, causing workspace exhaustion on subsequent pipelined fetch operations. EPSS score of 4.0 (low-to-medium risk) reflects attack complexity and limited scope (local availability impact only), though no public exploit code or active exploitation has been confirmed.
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.
Denial of service in Vinyl Cache releases before 9.0.2 (and in the related Varnish Cache lineage, per the affected CPEs): when the deployed VCL calls the .upper() or .lower() string methods on an attacker-influenced value, a carefully sized request string can overrun the remaining worker-thread workspace at that call site, causing the child process to segfault or trip an assertion and then restart. Reachability is gated by a non-default prerequisite - the VCL must actually apply these methods to request-derived data - and the attacker must know that VCL logic well enough to size the string to land in the narrow window between filling the remaining workspace and the http_req_size / http_req_hdr_len request limits, so this is a deliberately low-priority memory-corruption issue rather than a general-purpose remote attack. No public exploit code has been identified at time of analysis, and the impact is a transient, self-healing outage rather than a persistent one, with no effect on confidentiality or integrity.
Varnish Cache before 7.6.2 and Varnish Enterprise before 6.0.13r10 allow client-side desync via HTTP/1 requests. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
An HTTP Request Forgery issue was discovered in Varnish Cache 5.x and 6.x before 6.0.11, 7.x before 7.1.2, and 7.2.x before 7.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache 7.x before 7.1.2 and 7.2.x before 7.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In Varnish Cache 7.0.0, 7.0.1, 7.0.2, and 7.1.0, it is possible to cause the Varnish Server to assert and automatically restart through forged HTTP/1 backend responses. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This HTTP Request/Response Smuggling vulnerability could allow attackers to manipulate HTTP request interpretation between frontend and backend servers.
Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache before 6.0.6 LTS, 6.1.x and 6.2.x before 6.2.3, and 6.3.x before 6.3.2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache before 6.0.4 LTS, and 6.1.x and 6.2.x before 6.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
vbf_stp_error in bin/varnishd/cache/cache_fetch.c in Varnish HTTP Cache 4.1.x before 4.1.9 and 5.x before 5.2.1 allows remote attackers to obtain sensitive information from process memory because a. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.
An issue was discovered in Varnish HTTP Cache 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Varnish 3.x before 3.0.7, when used in certain stacked installations, allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via a header line terminated. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
varnish 3.0.3 uses world-readable permissions for the /var/log/varnish/ directory and the log files in the directory, which allows local users to obtain sensitive information by reading the files. Rated low severity (CVSS 2.1), this vulnerability is low attack complexity. No vendor patch available.
Varnish before 3.0.5 allows remote attackers to cause a denial of service (child-process crash and temporary caching outage) via a GET request with trailing whitespace characters and no URI. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
Varnish Cache 9.0.0 crashes (denial of service) when a remote client exploits timing between timeout_linger and timeout_idle to trigger HTTP/1 request pipelining that causes a workspace overflow in the refactored HTTP/2 architecture. The vulnerability stems from incomplete code path handling during workspace rollback in the recent non-blocking port, allowing prefetched data to exceed workspace_client boundaries and panic the daemon. Vendor-released patch: version 9.0.1. No public exploit code identified at time of analysis, but the attack requires only network access and careful timing, making real-world exploitation feasible for sophisticated attackers.
Denial of service via workspace overflow in Varnish Cache 9 before 9.0.1 and Varnish Enterprise before 6.0.16r11 allows unauthenticated remote attackers to trigger daemon panic through HTTP/2 session upgrade with specific amounts of prefetched data. The vulnerability exploits improper buffer allocation during HTTP/1 to HTTP/2 transport upgrade, causing workspace exhaustion on subsequent pipelined fetch operations. EPSS score of 4.0 (low-to-medium risk) reflects attack complexity and limited scope (local availability impact only), though no public exploit code or active exploitation has been confirmed.
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.
Denial of service in Vinyl Cache releases before 9.0.2 (and in the related Varnish Cache lineage, per the affected CPEs): when the deployed VCL calls the .upper() or .lower() string methods on an attacker-influenced value, a carefully sized request string can overrun the remaining worker-thread workspace at that call site, causing the child process to segfault or trip an assertion and then restart. Reachability is gated by a non-default prerequisite - the VCL must actually apply these methods to request-derived data - and the attacker must know that VCL logic well enough to size the string to land in the narrow window between filling the remaining workspace and the http_req_size / http_req_hdr_len request limits, so this is a deliberately low-priority memory-corruption issue rather than a general-purpose remote attack. No public exploit code has been identified at time of analysis, and the impact is a transient, self-healing outage rather than a persistent one, with no effect on confidentiality or integrity.
Varnish Cache before 7.6.2 and Varnish Enterprise before 6.0.13r10 allow client-side desync via HTTP/1 requests. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
An HTTP Request Forgery issue was discovered in Varnish Cache 5.x and 6.x before 6.0.11, 7.x before 7.1.2, and 7.2.x before 7.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache 7.x before 7.1.2 and 7.2.x before 7.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In Varnish Cache 7.0.0, 7.0.1, 7.0.2, and 7.1.0, it is possible to cause the Varnish Server to assert and automatically restart through forged HTTP/1 backend responses. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This HTTP Request/Response Smuggling vulnerability could allow attackers to manipulate HTTP request interpretation between frontend and backend servers.
Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache before 6.0.6 LTS, 6.1.x and 6.2.x before 6.2.3, and 6.3.x before 6.3.2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in Varnish Cache before 6.0.4 LTS, and 6.1.x and 6.2.x before 6.2.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
vbf_stp_error in bin/varnishd/cache/cache_fetch.c in Varnish HTTP Cache 4.1.x before 4.1.9 and 5.x before 5.2.1 allows remote attackers to obtain sensitive information from process memory because a. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.
An issue was discovered in Varnish HTTP Cache 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Varnish 3.x before 3.0.7, when used in certain stacked installations, allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via a header line terminated. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
varnish 3.0.3 uses world-readable permissions for the /var/log/varnish/ directory and the log files in the directory, which allows local users to obtain sensitive information by reading the files. Rated low severity (CVSS 2.1), this vulnerability is low attack complexity. No vendor patch available.
Varnish before 3.0.5 allows remote attackers to cause a denial of service (child-process crash and temporary caching outage) via a GET request with trailing whitespace characters and no URI. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.