Denial of Service Vulnerability in next.js

Impact

Vulnerable code could allow a bad actor to trigger a denial of service attack for anyone running a Next.js app at version >= 12.0.0, and using i18n functionality.

• Affected: All of the following must be true to be affected by this CVE
  • Next.js versions above v12.0.0
  • Using next start or a custom server
  • Using the built-in i18n support
• Not affected:
  • Deployments on Vercel (vercel.com) are not affected along with similar environments where invalid requests are filtered before reaching Next.js.

Patches

A patch has been released, next@12.0.9, that mitigates this issue. We recommend all affected users upgrade as soon as possible.

Workarounds

We recommend upgrading whether you can reproduce or not although you can ensure /${locale}/_next/ is blocked from reaching the Next.js instance until you upgrade.

For more information

If you have any questions or comments about this advisory:

• Open an issue in next
• Email us at security@vercel.com