GHSA-XMF8-CVQR-RFGJ

Vulnerability from github – Published: 2026-07-23 14:42 – Updated: 2026-08-13 19:05
VLAI
Summary
Auth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers
Details

Summary

The exported getToken() helper (next-auth/jwt and @auth/core/jwt) can throw an uncaught exception when it reads a malformed Authorization: Bearer … header. When no session cookie is present, getToken() URL-decodes the bearer value before validating it, and malformed percent-encoding causes the decode step to throw rather than being treated as an invalid token. Because getToken() is commonly called in API routes, middleware, and other request handlers, a single unauthenticated request can trigger an unhandled exception in code paths that authenticate requests.

Am I affected?

You are affected if all of the following hold:

  • You use next-auth <= 5.0.0-beta.25 (or @auth/core exposing the same getToken() implementation).
  • Your application calls getToken() directly — for example in a Route Handler, middleware, or server-side request handler.
  • You do not wrap that getToken() call in your own try/catch.

You are not affected if you only use the framework's auth() helper and never call getToken() yourself, or if every getToken() call site already has its own exception handling.

Impact

  • Denial of service: an unauthenticated request carrying a malformed Bearer authorization header can raise an unhandled exception in any handler that calls getToken().
  • The impact is per-request and limited to availability; it does not expose tokens, sessions, or other data, and does not bypass authentication.

CWE-20: Improper Input Validation.

Patched version

The fix makes getToken() treat a malformed Bearer value as an invalid token and return null, matching how other undecodable tokens are already handled. Upgrade to the first release containing this fix (to be published; this advisory will be updated with the exact patched version before publication) and no code changes are required.

Workarounds

If you cannot upgrade immediately, either:

  • Config/code-level: wrap your getToken() calls so a thrown error is treated as "no token", e.g.

ts let token = null try { token = await getToken({ req, secret }) } catch { token = null }

  • Or strip/normalize the incoming Authorization header at the edge (proxy, middleware) before it reaches getToken(), rejecting values whose Bearer portion is not valid percent-encoding.

Credit

Reported by @deprrous. Thank you for the responsible disclosure.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@auth/core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.1.0"
            },
            {
              "fixed": "0.41.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.0.0-beta.31"
      },
      "package": {
        "ecosystem": "npm",
        "name": "next-auth"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0-beta.0"
            },
            {
              "fixed": "5.0.0-beta.32"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.24.14"
      },
      "package": {
        "ecosystem": "npm",
        "name": "next-auth"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.6"
            },
            {
              "fixed": "4.24.15"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-73418"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-23T14:42:55Z",
    "nvd_published_at": "2026-08-12T21:17:40Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe exported `getToken()` helper (`next-auth/jwt` and `@auth/core/jwt`) can throw an uncaught exception when it reads a malformed `Authorization: Bearer \u2026` header. When no session cookie is present, `getToken()` URL-decodes the bearer value before validating it, and malformed percent-encoding causes the decode step to throw rather than being treated as an invalid token. Because `getToken()` is commonly called in API routes, middleware, and other request handlers, a single unauthenticated request can trigger an unhandled exception in code paths that authenticate requests.\n\n## Am I affected?\n\nYou are affected if **all** of the following hold:\n\n- You use `next-auth` `\u003c= 5.0.0-beta.25` (or `@auth/core` exposing the same `getToken()` implementation).\n- Your application calls `getToken()` directly \u2014 for example in a Route Handler, middleware, or server-side request handler.\n- You do not wrap that `getToken()` call in your own `try/catch`.\n\nYou are **not** affected if you only use the framework\u0027s `auth()` helper and never call `getToken()` yourself, or if every `getToken()` call site already has its own exception handling.\n\n## Impact\n\n- Denial of service: an unauthenticated request carrying a malformed Bearer authorization header can raise an unhandled exception in any handler that calls `getToken()`.\n- The impact is per-request and limited to availability; it does not expose tokens, sessions, or other data, and does not bypass authentication.\n\nCWE-20: Improper Input Validation.\n\n## Patched version\n\nThe fix makes `getToken()` treat a malformed Bearer value as an invalid token and return `null`, matching how other undecodable tokens are already handled. Upgrade to the first release containing this fix (to be published; this advisory will be updated with the exact patched version before publication) and no code changes are required.\n\n## Workarounds\n\nIf you cannot upgrade immediately, either:\n\n- **Config/code-level:** wrap your `getToken()` calls so a thrown error is treated as \"no token\", e.g.\n\n  ```ts\n  let token = null\n  try {\n    token = await getToken({ req, secret })\n  } catch {\n    token = null\n  }\n  ```\n\n- Or strip/normalize the incoming `Authorization` header at the edge (proxy, middleware) before it reaches `getToken()`, rejecting values whose Bearer portion is not valid percent-encoding.\n\n## Credit\n\nReported by @deprrous. Thank you for the responsible disclosure.",
  "id": "GHSA-xmf8-cvqr-rfgj",
  "modified": "2026-08-13T19:05:18Z",
  "published": "2026-07-23T14:42:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/security/advisories/GHSA-xmf8-cvqr-rfgj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-73418"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/pull/13467"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/pull/13469"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/commit/5bca2399a79ba8d116ca5179b4b1ebcd152e7f05"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/commit/e707770f00c52b3479e43422b0200b059149ed53"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nextauthjs/next-auth"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Auth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers"
}



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