CVE-2026-44575: Vercel Next.js

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

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

• Vercel Next.js: from 15.2.0, before 15.5.16 (fixed in 15.5.16); from 16.0.0, before 16.2.5 (fixed in 16.2.5)

Published 2026-05-13. Last modified 2026-08-13.