Next.js: Middleware / Proxy redirects can be cache-poisoned
Title source: cnaExploitation Summary
EIP tracks 2 public exploits for CVE-2026-44572. PoCs published by dwisiswant0, XZ1r0.
AI-analyzed exploit summary This repository contains functional proof-of-concept exploits for multiple CVEs affecting Next.js v16.2.4, including SSRF, XSS, DoS, and cache poisoning vulnerabilities. The PoCs are well-documented with detailed write-ups, vulnerable code excerpts, and runnable exploit scripts.
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, an external client could send a x-nextjs-data header on a normal request to a path handled by middleware that returns a redirect. When that happened, the middleware/proxy could treat the request as a data request and replace the standard Location redirect header with the internal x-nextjs-redirect header. Browsers do not follow x-nextjs-redirect, so the response became an unusable redirect for normal clients. If the application was deployed behind a CDN or reverse proxy that caches 3xx responses without varying on this header, a single attacker request could poison the cached redirect response for the affected path. Subsequent visitors could then receive a cached redirect response without a Location header, causing a denial of service for that redirect path until the cache entry expired or was purged. This vulnerability is fixed in 15.5.16 and 16.2.5.
Exploits (2)
This repository contains functional proof-of-concept exploits for multiple CVEs affecting Next.js v16.2.4, including SSRF, XSS, DoS, and cache poisoning vulnerabilities. The PoCs are well-documented with detailed write-ups, vulnerable code excerpts, and runnable exploit scripts.
This repository contains a functional exploit for CVE-2026-44572, demonstrating how an attacker can manipulate the `x-nextjs-data` header to convert a legitimate 307 redirect into a malformed 200 OK response, leading to cache poisoning and DoS in Next.js versions <= 16.2.4.
References (1)
Scores
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L