Description
Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically "Deny" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.
Problem types
CWE-863: Incorrect Authorization
Product status
>= 1.36.0, < 1.36.5
>= 1.35.0, < 1.35.9
< 1.34.13
References
github.com/.../envoy/security/advisories/GHSA-ghc4-35x6-crw5
github.com/...ommit/b6ba0b2294b98484fb0ed8556897d1073cc27867