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HIGH

Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes

Published May 13, 2026

Description

Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.16 and 16.2.5, App Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted .rsc and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check. This vulnerability is fixed in 15.5.16 and 16.2.5.

Affected products

Remediation

Red Hat statement

This is an Important flaw in Next.js App Router applications that utilize middleware or proxy-based authorization. A remote attacker can bypass these security checks by crafting specific URLs, leading to unauthorized access to protected content. This is due to transport-specific route variants used for segment prefetching not being consistently matched by middleware rules.

Red Hat mitigation

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.

Metrics

Weaknesses (2)

CWE-288

CWE-551

References (13)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner GitHub_M
Published May 13, 2026
Updated Aug 13, 2026
Reserved May 6, 2026
Link CVE-2026-44575
CISA Vulnrichment
Updated May 13, 2026
NVD
Status Modified
Modified Aug 13, 2026
Link CVE-2026-44575
Red Hat
Severity Important
Public date May 13, 2026
Links CVE-2026-44575 - Bugzilla
GHSA-267C-6GRR-H53F