Vulnerability · Published May 13, 2026 · Assigned by GitHub_M
CVE-2026-44572Next.js: Middleware / Proxy redirects can be cache-poisoned
Low 3.7
In plain English
A low-severity security flaw in next.js from vercel. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | next | 15.5.16 | GHSA-3g8h-86w9-wvmq |
| npm | next | 16.2.5 | GHSA-3g8h-86w9-wvmq |
Affected products (as reported)
Weakness: CWE-349 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- https://github.com/vercel/next.js/security/advisories/GHSA-3g8h-86w9-wvmq x_refsource_CONFIRM