{"id":"BIT-envoy-2026-26308","summary":"Envoy has an RBAC Header Validation Bypass via Multi-Value Header Concatenation","details":"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.","aliases":["CVE-2026-26308","GHSA-ghc4-35x6-crw5"],"modified":"2026-09-08T08:47:31.777064843Z","published":"2026-03-12T08:39:41.078Z","database_specific":{"severity":"High","cpes":["cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:go:*:*"]},"references":[{"type":"FIX","url":"https://github.com/envoyproxy/envoy/commit/b6ba0b2294b98484fb0ed8556897d1073cc27867"},{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-ghc4-35x6-crw5"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26308"}],"affected":[{"package":{"name":"envoy","ecosystem":"Bitnami","purl":"pkg:bitnami/envoy"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.34.13"},{"introduced":"1.35.0"},{"fixed":"1.35.9"},{"introduced":"1.36.0"},{"fixed":"1.36.5"},{"introduced":"1.37.0"},{"fixed":"1.37.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/envoy/BIT-envoy-2026-26308.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N"}]}],"schema_version":"1.9.0"}