CVE-2026-44573

A flaw was found in Next.js. Applications utilizing the Pages Router with internationalization (i18n) configured and middleware or proxy-based authorization are susceptible to unauthorized access. A remote attacker can exploit this by making locale-less /_next/data/<buildId>/<page>.json requests, which bypass the intended authorization checks. This allows the attacker to retrieve sensitive server-side rendered (SSR) JSON data from protected pages, leading to information disclosure.

Important: A flaw in Next.js applications allows unauthorized access to sensitive server-side rendered (SSR) JSON data by bypassing middleware authorization checks. This occurs when applications use the Pages Router with internationalization (i18n) and middleware or proxy-based authorization, enabling remote attackers to retrieve protected page data through locale-less requests.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.