What’s Vulnerable › Vulnerabilities

CVE-2025-29927: Authorization Bypass in Next.js Middleware

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 99.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-03-21 · updated 2026-06-17
• Weakness: CWE-285

Description

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.

Affected products

• Next.js: from 11.1.4 before 12.3.5; from 13.0.0 before 13.5.9; from 14.0.0 before 14.2.25; from 15.0.0 before 15.2.3 — fixed in 12.3.5, 13.5.9, 14.2.25, 15.2.3
• Npm Next: from 13.0.0 before 13.5.9; from 14.0.0 before 14.2.25; from 15.0.0 before 15.2.3; from 12.0.0 before 12.3.5 — fixed in 13.5.9, 14.2.25, 15.2.3, 12.3.5

How to fix

Upgrade to a fixed version: Next.js 12.3.5, 13.5.9, 14.2.25, 15.2.3; Npm Next 13.5.9, 14.2.25, 15.2.3, 12.3.5. Check the vendor advisory for mitigations.

References

• https://github.com/vercel/next.js/commit/52a078da3884efe6501613c7834a3d02a91676d2
• https://github.com/vercel/next.js/commit/5fd3ae8f8542677c6294f32d18022731eab6fe48
• https://github.com/vercel/next.js/releases/tag/v12.3.5
• https://github.com/vercel/next.js/releases/tag/v13.5.9
• https://github.com/vercel/next.js/security/advisories/GHSA-f82v-jwr5-mffw
• http://www.openwall.com/lists/oss-security/2025/03/23/3
• http://www.openwall.com/lists/oss-security/2025/03/23/4
• https://security.netapp.com/advisory/ntap-20250328-0002/

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