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Fencer Intel
medium 5.4

CVE-2026-40155 json

Auth0 Next.js SDK has Improper Proxy Cache Lookup

published 6mo ago modified 4mo ago also EUVD-2026-23537 , GHSA-xq8m-7c5p-c2r6

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

The Auth0 Next.js SDK is a library for implementing user authentication in Next.js applications. In versions 4.12.0 through 4.17.1, simultaneous requests that trigger a nonce retry may cause the proxy cache fetcher to perform improper lookups for the token request results. Users are affected if their project uses both the vulnerable versions and the proxy handler /me/* and /my-org/* with DPoP enabled. This issue has been fixed in version 4.18.0.

Patch / fix

  • npm @auth0/nextjs-auth0 4.18.0
  • auth0 nextjs-auth0 4.18.0

Is CVE-2026-40155 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm @auth0/nextjs-auth0
>=4.12.0, <4.18.0
4.18.0

Affected products

  • auth0 nextjs-auth0

Classification

Weakness
  • CWE-863 Incorrect Authorization
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.