CVE-2026-73418: NextAuth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
@auth/coreto a version that resolves this vulnerability.Fixed in 0.41.3 - Upgrade
Upgrade
next-authto a version that resolves this vulnerability.Fixed in 4.24.15 - Upgrade
Upgrade
next-authto a version that resolves this vulnerability.Fixed in 5.0.0-beta.32
Event History
Frequently Asked Questions
What is the severity of CVE-2026-73418?
CVE-2026-73418 has a high severity rating of 7.5 based on the CVSS score.
How do I fix CVE-2026-73418?
To fix CVE-2026-73418, upgrade to @auth/core version 0.41.3 or next-auth versions 4.24.15 and 5.0.0-beta.32 or later.
What does CVE-2026-73418 affect?
CVE-2026-73418 affects the getToken() helper in the next-auth/jwt and @auth/core/jwt modules of NextAuth.js.
What type of vulnerability is CVE-2026-73418?
CVE-2026-73418 is categorized as an Input Validation vulnerability.
What happens when a malformed Bearer authorization header is used with CVE-2026-73418?
Using a malformed Bearer authorization header with CVE-2026-73418 can result in an uncaught exception being thrown.