CVE-2026-44575 — Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes

Description (CNA)

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 (CNA)

Vendor / product	Versions
vercel / next.js	affected >= 16.0.0, < 16.2.5; affected >= 15.2.0, < 15.5.16

CWE

CWE-288

References

https://github.com/vercel/next.js/security/advisories/GHSA-267c-6grr-h53f

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in Next.js. App Router applications that use middleware or proxy-based authorization checks are vulnerable to unauthorized access. A remote attacker can exploit this by crafting specific .rsc and segment-prefetch URLs, which bypass the intended middleware rules. This allows access to protected content without proper authorization.