{"id":"GHSA-46wh-3698-f2cx","summary":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)","details":"## Summary\n\nThere is a potential vulnerability in Traefik due to its dependency on an affected version of gRPC-Go (CVE-2026-33186).\n\nA remote, unauthenticated attacker can send gRPC requests with a malformed HTTP/2 `:path` pseudo-header omitting the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server routes such requests correctly, path-based authorization interceptors evaluate the raw non-canonical path and fail to match \"deny\" rules, allowing the request to bypass the policy entirely if a fallback \"allow\" rule is present.\n\n## Patches\n\n- https://github.com/traefik/traefik/releases/tag/v2.11.42\n- https://github.com/traefik/traefik/releases/tag/v3.6.12\n- https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3\n\n## For more information\n\nIf there are any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).\n\n\u003cdetails\u003e\n\u003csummary\u003eOriginal Description\u003c/summary\u003e\n\n### Summary\nThis CVE hits traefik until Version 3.6.11 and 2.11.41.\ngRPC-Go has an authorization bypass via missing leading slash in :path\n### Details\nAs described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3\n### PoC\nUpdate library version in \nhttps://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108\n### Impact\nIs described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3\n\n\u003c/details\u003e\n\n\n----------","aliases":["GO-2026-4897"],"modified":"2026-09-10T03:50:36.980577799Z","published":"2026-03-29T15:37:28Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-03-29T15:37:28Z","nvd_published_at":null,"cwe_ids":["CWE-1395","CWE-285"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/traefik/traefik/security/advisories/GHSA-46wh-3698-f2cx"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-p77j-4mvh-x3m3"},{"type":"PACKAGE","url":"https://github.com/traefik/traefik"},{"type":"WEB","url":"https://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108"},{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v2.11.42"},{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.6.12"},{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3"}],"affected":[{"package":{"name":"github.com/traefik/traefik/v2","ecosystem":"Go","purl":"pkg:golang/github.com/traefik/traefik/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.42"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-46wh-3698-f2cx/GHSA-46wh-3698-f2cx.json"}},{"package":{"name":"github.com/traefik/traefik/v3","ecosystem":"Go","purl":"pkg:golang/github.com/traefik/traefik/v3"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0-beta3"},{"fixed":"3.6.12"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-46wh-3698-f2cx/GHSA-46wh-3698-f2cx.json"}},{"package":{"name":"github.com/traefik/traefik/v3","ecosystem":"Go","purl":"pkg:golang/github.com/traefik/traefik/v3"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.7.0-ea.1"},{"fixed":"3.7.0-ea.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-46wh-3698-f2cx/GHSA-46wh-3698-f2cx.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N"}]}