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.

Timeline

1. Aug 12, 2026, 8:21 PM UTCCVE published1 day
2. Aug 13, 2026, 12:53 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Aug 13, 2026, 12:53 PM UTCRecord last updated

Affected versions

• nextauthjs next-auth

  From 4.0.6 · through 4.24.14; From 5.0.0-beta.0 · through 5.0.0-beta.31

• @auth core

  From 0.1.0 · fixed in 0.41.3

• @auth/corenpm

  From 0.1.0 · fixed in 0.41.3

• next-authnpm

  From 5.0.0-beta.0 · fixed in 5.0.0-beta.32

• next-authnpm

  From 4.0.6 · fixed in 4.24.15

References 7