Vulnerability-Lookup

CVE-2026-73418 (GCVE-0-2026-73418)

Vulnerability from cvelistv5 – Published: 2026-08-12 20:21 – Updated: 2026-08-13 12:53

Title

NextAuth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers

Summary

NextAuth.js provides authentication for Next.js. Prior to @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32, the exported getToken() helper in the next-auth/jwt and @auth/core/jwt modules 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 decodeURIComponent() to throw instead of treating the token as invalid. Because getToken() is commonly called in API routes, middleware, and server-side request handlers, a single unauthenticated request can trigger an unhandled exception in code paths that authenticate requests, causing a per-request denial of service without exposing tokens, sessions, or other data and without bypassing authentication. This issue is fixed in @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-13 12:53 UTC

CWE

CWE-20 - Improper Input Validation
CWE-248 - Uncaught Exception

Assigner

GitHub_M

References

7 references

URL	Tags
https://github.com/nextauthjs/next-auth/security/…	x_refsource_CONFIRM
https://github.com/nextauthjs/next-auth/pull/13469	x_refsource_MISC
https://github.com/nextauthjs/next-auth/commit/5b…	x_refsource_MISC
https://github.com/nextauthjs/next-auth/commit/e7…	x_refsource_MISC
https://github.com/nextauthjs/next-auth/releases/…	x_refsource_MISC
https://github.com/nextauthjs/next-auth/releases/…	x_refsource_MISC
https://github.com/nextauthjs/next-auth/releases/…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
nextauthjs	next-auth	Affected: >= 4.0.6, <= 4.24.14 Affected: >= 5.0.0-beta.0, <= 5.0.0-beta.31
@auth	core	Affected: >= 0.1.0, < 0.41.3

Show details on NVD website

JSON

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GHSA-XMF8-CVQR-RFGJ

Vulnerability from github – Published: 2026-07-23 14:42 – Updated: 2026-08-13 19:05

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

JSON

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    "cwe_ids": [
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    "github_reviewed": true,
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    "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-73418 (GCVE-0-2026-73418)

GHSA-XMF8-CVQR-RFGJ

Summary

Am I affected?

Impact

Patched version

Workarounds

Credit

Tags

Sightings

Nomenclature