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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-36qx-fr4f-26g5 Next.js has a Middleware / Proxy bypass in Pages Router applications using i18n
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 13 May 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 13 May 2026 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Vercel
Vercel next.js
Vendors & Products Vercel
Vercel next.js

Wed, 13 May 2026 17:15:00 +0000

Type Values Removed Values Added
Description 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.
Title Next.js: Middleware / Proxy bypass in Pages Router applications using i18n
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-13T18:19:49.658Z

Reserved: 2026-05-06T21:49:12.424Z

Link: CVE-2026-44573

cve-icon Vulnrichment

Updated: 2026-05-13T18:11:24.593Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-13T17:16:22.627

Modified: 2026-05-13T17:25:25.693

Link: CVE-2026-44573

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-13T19:00:15Z

Weaknesses