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CVE-2026-44573

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

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 /_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. This vulnerability is fixed in 15.5.16 and 16.2.5.

CVSS 7.5 · High · EPSS 0.8% · Fix available

Published
Updated

Stack: node

Affected products and versions

  • next.js

    Versions
    • >= 12.2.0, < 15.5.16: Affected
    • >= 16.0.0, < 16.2.5: Affected

    No fix published

  • next npm

    Affected ranges
    • SEMVER: ≥ 12.2.0, < 15.5.16

    Update to 15.5.16

  • next npm

    Affected ranges
    • SEMVER: ≥ 16.0.0, < 16.2.5

    Update to 16.2.5

Original sources

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