What is CVE-2025-29927?

CVE-2025-29927 is a critical-severity vulnerability in Vercel Next.js, classified under Improper Authorization. CVSS score: 9.1/10. Published 2025-03-21.

How severe is CVE-2025-29927?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Is CVE-2025-29927 known to be exploited?

786 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Auth bypass in Vercel Next.js

CVE-2025-29927

Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware. If patching to a safe version is infeasible, it is recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application. This vulnerability is fixed in 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

Published 2025-03-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.992 (99.9th percentile), scored 2026-10-18.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 99.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.992 · newest: 0.992 · change: 0.000

Affected products

Vercel Next.js — versions >= 11.1.4, < 12.3.5, >= 14.0.0, < 14.2.25, >= 15.0.0, < 15.2.3

Weakness classification (CWE)

Public proof-of-concept exploits

References

github.com/vercel/next.js/security/advisories/GHSA-f82v-jwr5-mffw (Vendor Advisory)
github.com/vercel/next.js/commit/52a078da3884efe6501613c7834a3d02a91676d2 (Patch)
github.com/vercel/next.js/commit/5fd3ae8f8542677c6294f32d18022731eab6fe48 (Patch)
github.com/vercel/next.js/releases/tag/v12.3.5 (Release Notes)
github.com/vercel/next.js/releases/tag/v13.5.9 (Release Notes)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List)
af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)

Frequently asked questions

What is CVE-2025-29927?: CVE-2025-29927 is a critical-severity vulnerability in Vercel Next.js, classified under Improper Authorization. CVSS score: 9.1/10. Published 2025-03-21.
How severe is CVE-2025-29927?: Critical severity. CVSS v3 base score is 9.1 out of 10.
Is CVE-2025-29927 known to be exploited?: 786 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.