What’s Vulnerable › Vulnerabilities
CVE-2026-44572: Next.js: Middleware / Proxy redirects can be cache-poisoned
- Severity: medium (CVSS 5.9 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-13 · updated 2026-10-26
- Weakness: CWE-349
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 products
- Next.js: from 12.2.0 before 15.5.16; from 16.0.0 before 16.2.5 — fixed in 15.5.16, 16.2.5
- Npm Next: from 12.2.0 before 15.5.16; from 16.0.0 before 16.2.5 — fixed in 15.5.16, 16.2.5
How to fix
Upgrade to a fixed version: Next.js 15.5.16, 16.2.5; Npm Next 15.5.16, 16.2.5. Check the vendor advisory for mitigations.
References
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