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GHSA-46WH-3698-F2CX

Vulnerability from github – Published: 2026-03-29 15:37 – Updated: 2026-03-29 15:37
VLAI
Summary
Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)
Details

Summary

There is a potential vulnerability in Traefik due to its dependency on an affected version of gRPC-Go (CVE-2026-33186).

A 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.

Patches

  • https://github.com/traefik/traefik/releases/tag/v2.11.42
  • https://github.com/traefik/traefik/releases/tag/v3.6.12
  • https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3

For more information

If there are any questions or comments about this advisory, please open an issue.

Original Description ### Summary This CVE hits traefik until Version 3.6.11 and 2.11.41. gRPC-Go has an authorization bypass via missing leading slash in :path ### Details As described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3 ### PoC Update library version in https://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108 ### Impact Is described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3
Severity
7.8 (High)
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
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/traefik/traefik/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.11.42"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/traefik/traefik/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0-beta3"
            },
            {
              "fixed": "3.6.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/traefik/traefik/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.7.0-ea.1"
            },
            {
              "fixed": "3.7.0-ea.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-1395",
      "CWE-285"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-29T15:37:28Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "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----------",
  "id": "GHSA-46wh-3698-f2cx",
  "modified": "2026-03-29T15:37:29Z",
  "published": "2026-03-29T15:37:28Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)"
}



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