WAF Emergency Release: Next.js Middleware Bypass Detection (CVE-2026-44575)

This emergency release introduces a new rule to detect Next.js App Router middleware and proxy bypass attempts via segment-prefetch routes (CVE-2026-44575).

Key Findings

CVE-2026-44575: Next.js Middleware / Proxy Bypass in App Router Applications via Segment-Prefetch Routes

Successful exploitation allows unauthenticated attackers to bypass middleware or proxy-based authorization checks in affected Next.js App Router applications. This leads to unauthorized access to protected content, potential exposure of sensitive application data, and compromise of application security boundaries.

We strongly recommend upgrading to Next.js 15.5.16 or 16.2.5 (or later) immediately to address the underlying vulnerability. If you cannot upgrade immediately, enforce authorization in the underlying route or page logic instead of relying solely on middleware.

Ruleset	Rule ID	Legacy Rule ID	Description	Previous Action	New Action	Comments
Cloudflare Managed Ruleset	...e77e4a53	N/A	Next.js - Middleware Bypass via Invalid RSC Header - CVE:CVE-2026-44575	N/A	Disabled	This is a new detection.