CVE-2026-44573 Next.js: Middleware / Proxy bypass in Pages Router applications using i18n

Next.js is a React framework for building full-stack web applications. From 12.2.0 to before 15.5.16 and 16.2.5, Applications using the Pages Router with i18n configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less...

CVE-2026-44573

CVE-2026-44573 affects Next.js (Pages Router with i18n). From 12.2.0 up to but not including 15.5.16 and 16.2.5, middleware/proxy-based authorization can be bypassed for locale-less /_next/data//.json requests, allowing retrieval of SSR JSON for protected pages without authorization checks. The u...