Istio
CVE-2026-31838
MEDIUM
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
2DescriptionGitHub Advisory
Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a vulnerability in Envoy RBAC header matching could allow authorization policy bypass when policies rely on HTTP headers that may contain multiple values. An attacker could craft requests with multiple header values in a way that causes Envoy to evaluate the header differently than intended, potentially bypassing authorization checks. This may allow unauthorized requests to reach protected services when policies depend on such header-based matching conditions. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.
AnalysisAI
Istio versions prior to 1.29.1, 1.28.5, and 1.27.8 are vulnerable to authorization policy bypass through improper Envoy RBAC handling of multi-valued HTTP headers. An attacker can craft requests with multiple header values that cause the authorization engine to evaluate headers differently than intended, allowing unauthorized access to protected microservices. No patch is currently available for this vulnerability.
Technical ContextAI
Classified as CWE-863 (Incorrect Authorization). Affects and secure microservices.. Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a vulnerability in Envoy RBAC header matching could allow authorization policy bypass when policies rely on HTTP headers that may contain multiple values. An attacker could craft requests with multiple header values in a way that causes Envoy to evaluate the header differently than intended, potentially bypassing authorization checks. This may allow unauthorized requests to reach protecte
RemediationAI
Fixed in version 1.29.1.
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour
Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability where an external client can acc
Istio 1.3.x before 1.3.5 allows Denial of Service because continue_on_listener_filters_timeout is set to True, a related
Envoy 1.12.0 allows a remote denial of service because of resource loops, as demonstrated by a single idle TCP connectio
Istio before 1.1.13 and 1.2.x before 1.2.4 mishandles regular expressions for long URIs, leading to a denial of service
Istio 1.1.x through 1.1.6 has Incorrect Access Control. Rated high severity (CVSS 7.5), this vulnerability is no authent
In Istio 1.5.0 though 1.5.8 and Istio 1.6.0 through 1.6.7, when users specify an AuthorizationPolicy resource with DENY
Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multi
Istio is an open platform to connect, manage, and secure microservices. Rated critical severity (CVSS 9.8), this vulnera
Istio (1.8.x, 1.9.0-1.9.5 and 1.10.0-1.10.1) contains a remotely exploitable vulnerability where credentials specified i
Authentication enforcement in Istio service mesh fails open: prior to 1.29.1, 1.28.5, and 1.27.8, when the JWKS resolver
Istio is an open platform-independent service mesh that provides traffic management, policy enforcement, and telemetry c
Same weakness CWE-863 – Incorrect Authorization
View allSame technique Authentication Bypass
View allVendor StatusVendor
SUSE
Severity: MediumShare
External POC / Exploit Code
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