{"schemaVersion":3,"id":"CVE-2026-26308","aliases":["GHSA-ghc4-35x6-crw5","BIT-envoy-2026-26308"],"status":"published","duplicateOf":null,"title":null,"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. 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