GHSA-36qx-fr4f-26g5
Next.js has a Middleware / Proxy bypass in Pages Router applications using i18n
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### Impact
Applications using the Pages Router with `i18n` configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less `/_next/data/<buildId>/<page>.json` requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks.
### Fix
The matcher logic was updated to perform the same match as it would on a non-i18n data route.
### Workarounds
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
References
External links from the advisory. They lead to third-party sites.