GHSA-46wh-3698-f2cx: Traefik Deny Rule Bypass Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-46wh-3698-f2cx",
  "modified" : "2026-03-29T15:37:29Z",
  "published" : "2026-03-29T15:37:28Z",
  "aliases" : [ ],
  "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<details>\n<summary>Original Description</summary>\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</details>\n\n\n----------",
  "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/traefik/traefik/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.11.42"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/traefik/traefik/v3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0-beta3"
      }, {
        "fixed" : "3.6.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/traefik/traefik/v3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.7.0-ea.1"
      }, {
        "fixed" : "3.7.0-ea.3"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1395", "CWE-285" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-29T15:37:28Z",
    "nvd_published_at" : null
  }
}