CVE-2025-29927

Workaround

If patching to a safe version is infeasible, we recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application.

Credits

• Allam Rachid (zhero;)
• Allam Yasser (inzo_)

It is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2025-29927 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (13.5.9, 14.2.25, 15.2.3, 12.3.5); upgrading removes the vulnerable code path.

Kodem intelligence

• For Next.js 15.x, this issue is fixed in 15.2.3
• For Next.js 14.x, this issue is fixed in 14.2.25
• For Next.js 13.x, this issue is fixed in 13.5.9
• For Next.js 12.x, this issue is fixed in 12.3.5
• For Next.js 11.x, consult the below workaround.

Note: Next.js deployments hosted on Vercel are automatically protected against this vulnerability.

1. What is CVE-2025-29927? CVE-2025-29927 is a critical-severity incorrect authorization vulnerability in next (npm), affecting versions >= 13.0.0, < 13.5.9. It is fixed in 13.5.9, 14.2.25, 15.2.3, 12.3.5. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2025-29927? CVE-2025-29927 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of next are affected by CVE-2025-29927? next (npm) versions >= 13.0.0, < 13.5.9 is affected.
4. Is there a fix for CVE-2025-29927? Yes. CVE-2025-29927 is fixed in 13.5.9, 14.2.25, 15.2.3, 12.3.5. Upgrade to this version or later.
5. Is CVE-2025-29927 exploitable, and should I be worried? Whether CVE-2025-29927 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-29927 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-29927?
   • Upgrade next to 13.5.9 or later
   • Upgrade next to 14.2.25 or later
   • Upgrade next to 15.2.3 or later
   • Upgrade next to 12.3.5 or later