Next.js is a React framework. In versions of Next.js prior to 12.0.5 or 11.1.3, invalid or malformed URLs could lead to a server crash. In order to be affected by this issue, the deployment must use Next.js versions above 11.1.0 and below 12.0.5, Node.js above 15.0.0, and next start or a custom server. Deployments on Vercel are not affected, along with similar environments where invalid requests are filtered before reaching Next.js. Versions 12.0.5 and 11.1.3 contain patches for this issue.

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