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GHSA-xmf8-cvqr-rfgj

ADVISORY - github

Summary

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.

    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.

Common Weakness Enumeration (CWE)

ADVISORY - github

CWE-20⁠

Improper Input Validation

Impacted images

Advisories

GitHub

CREATED

UPDATED

ADVISORY IDGHSA-xmf8-cvqr-rfgj⁠
EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)
CWE-20⁠

CVSS SCORE

7.5high
PackageTypeOS NameOS VersionAffected RangesFix Versions
next-authnpm-->=4.0.6,<=4.24.144.24.15
@auth/corenpm-->=0.1.0,<0.41.30.41.3
next-authnpm-->=5.0.0-beta.0,<=5.0.0-beta.315.0.0-beta.32

CVSS:3 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification⁠.

The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

The vulnerable system can be exploited without interaction from any user.

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

There is no loss of confidentiality.

There is no loss of trust or accuracy within the impacted component.

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.