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Fencer Vulns
high 7.5

CVE-2026-73418 json

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

published 2026-07-23 3 mo ago modified 2026-09-10 1 mo ago also GHSA-xmf8-cvqr-rfgj , EUVD-2026-57552

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

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.

Patch / fix

  • npm @auth/core 0.41.3
  • npm next-auth 4.24.15, 5.0.0-beta.32

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm @auth/core
>=0.1.0, <0.41.3
0.41.3
npm next-auth
>=5.0.0-beta.0, <5.0.0-beta.32
>=4.0.6, <4.24.15
5.0.0-beta.32
4.24.15

Affected products

  • nextauthjs next-auth
  • @auth core

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.