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CRITICAL 9.1 npm

Authorization Bypass in Next.js Middleware

GHSA-f82v-jwr5-mffw · CVE-2025-29927

Published · Modified

Description

Impact

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

Patches

  • 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.

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_)

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