{"id":"GHSA-46wh-3698-f2cx","aliases":["GO-2026-4897"],"status":"published","title":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)","description":"## 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----------","severity":{"version":"4.0","score":7.8,"vector":"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","level":"high","from":"ghsa"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1395","CWE-285"],"published":"2026-03-29T15:37:28Z","modified":"2026-09-10T03:50:36Z","fixes":[{"ecosystem":"Go","package":"github.com/traefik/traefik/v2","fixed_in":["2.11.42"],"sources":["ghsa","osv"]},{"ecosystem":"Go","package":"github.com/traefik/traefik/v3","fixed_in":["3.6.12","3.7.0-ea.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/traefik/traefik/v2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11.42"}]}]},{"source":"ghsa","ecosystem":"Go","package":"github.com/traefik/traefik/v3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0-beta3"},{"fixed":"3.6.12"}]}]},{"source":"ghsa","ecosystem":"Go","package":"github.com/traefik/traefik/v3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.7.0-ea.1"},{"fixed":"3.7.0-ea.3"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik/v2","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.42"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik/v3","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0-beta3"},{"fixed":"3.6.12"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik/v3","ranges":[{"type":"SEMVER","events":[{"introduced":"3.7.0-ea.1"},{"fixed":"3.7.0-ea.3"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik","ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik/v2","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.42"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/traefik/traefik/v3","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0-beta3"},{"fixed":"3.6.12"},{"introduced":"3.7.0-ea.1"},{"fixed":"3.7.0-ea.3"}]}]}],"references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-46wh-3698-f2cx","tags":["web","advisory"]},{"url":"https://github.com/advisories/GHSA-p77j-4mvh-x3m3","tags":["advisory","web"]},{"url":"https://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108","tags":["web"]},{"url":"https://github.com/traefik/traefik/releases/tag/v2.11.42","tags":["web"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.6.12","tags":["web"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3","tags":["web"]},{"url":"https://github.com/advisories/GHSA-46wh-3698-f2cx"},{"url":"https://github.com/traefik/traefik","tags":["package"]}],"sources":{"ghsa":[{"id":"GHSA-46wh-3698-f2cx","title":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)","description":"## 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----------","status":"published","published":"2026-03-29T15:37:28Z","modified":"2026-03-29T15:37:30Z","cvss":[{"version":"4.0","score":7.8,"vector":"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","level":"high"}],"cwes":["CWE-285","CWE-1395"],"updated_at":"2026-11-02T14:39:44.97342Z"}],"osv":[{"id":"GHSA-46wh-3698-f2cx","title":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)","description":"## 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----------","status":"published","published":"2026-03-29T15:37:28Z","modified":"2026-09-10T03:50:36.980577799Z","cvss":[{"version":"4.0","score":7.8,"vector":"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","level":"high"}],"cwes":["CWE-1395","CWE-285"],"updated_at":"2026-11-02T15:46:36.434231Z"},{"id":"GO-2026-4897","title":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186) in github.com/traefik/traefik","description":"Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186) in github.com/traefik/traefik","status":"published","published":"2026-04-02T18:42:30Z","modified":"2026-04-07T03:44:12.238744185Z","updated_at":"2026-11-02T15:47:02.280725Z"}]}}