GHSA-WCRF-9VRR-854F

Vulnerability from github – Published: 2026-07-16 19:23 – Updated: 2026-07-16 19:23
VLAI
Summary
Envoy Gateway: Authentication Bypass via Improper Input Validation in EnvoyExtensionPolicy Lua Allows Secret Disclosure
Details

Impact

The to_absolute_normalized_path function (security.lua:28-43) does not collapse redundant path separators (// → /). On Linux, //etc/passwd is equivalent to /etc/passwd (POSIX path semantics), but is_critical_path fails to match the double-slash variant because //etc/passwd does not start with /etc/.

This allows Lua code submitted as an EnvoyExtensionPolicy to read arbitrary files from the gateway controller pod's filesystem during Strict validation (the default), including:

  • /etc/passwd
  • Kubernetes SA tokens via //var/run/secrets/kubernetes.io/serviceaccount/token
  • TLS certificates via //certs/...
  • Process environment via //proc/self/environ

These credentials can be used to read sensitive information from the K8s API Server or from the Gateway XDS server.

Patches

This has been patched in versions >= v1.7.4 and v1.8.1

  • Collapse redundant path separators (// to /) so double-slash variants like //etc/passwd and //var/run/secrets/... are matched by the critical-path check.
  • Rewrite the traversal check to reject any . or .. segment in any position and across both separator styles (catches /etc/./passwd, ./etc/passwd, /etc/.).

Workarounds

Please refer to the Warning section in Lua docs for measures to reduce risk.

Credits

Envoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/envoyproxy/gateway"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.8.0-rc.0"
            },
            {
              "fixed": "1.8.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/envoyproxy/gateway"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.7.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-53713"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-16T19:23:38Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nThe `to_absolute_normalized_path` function (security.lua:28-43) does not collapse redundant path separators (// \u2192 /). On Linux, `//etc/passwd` is equivalent to `/etc/passwd` (POSIX path semantics), but `is_critical_path` fails to match the double-slash variant because `//etc/passwd` does not start with `/etc/`.\n\nThis allows Lua code submitted as an `EnvoyExtensionPolicy` to read arbitrary files from the gateway controller pod\u0027s filesystem during Strict validation (the default), including:\n\n* `/etc/passwd`\n* Kubernetes SA tokens via `//var/run/secrets/kubernetes.io/serviceaccount/token`\n* TLS certificates via `//certs/...`\n* Process environment via `//proc/self/environ`\n\nThese credentials can be used to read sensitive information from the K8s API Server or from the Gateway XDS server.\n\n### Patches\n\nThis has been patched in versions \u003e= v1.7.4 and v1.8.1\n\n  - Collapse redundant path separators (`//` to `/`) so double-slash variants like `//etc/passwd` and `//var/run/secrets/...` are matched by the critical-path check.\n  - Rewrite the traversal check to reject any `.` or `..` segment in any position and across both separator styles (catches `/etc/./passwd`, `./etc/passwd`, `/etc/.`).\n\n### Workarounds\nPlease refer to the `Warning` section in [Lua docs](https://gateway.envoyproxy.io/v1.8/tasks/extensibility/lua/) for measures to reduce risk.\n\n### Credits\n\nEnvoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.",
  "id": "GHSA-wcrf-9vrr-854f",
  "modified": "2026-07-16T19:23:38Z",
  "published": "2026-07-16T19:23:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/envoyproxy/gateway/security/advisories/GHSA-wcrf-9vrr-854f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/envoyproxy/gateway"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Envoy Gateway: Authentication Bypass via Improper Input Validation in EnvoyExtensionPolicy Lua Allows Secret Disclosure"
}



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