Vulnerability in Vercel Next.js
CVE-2026-44572
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.002 (9.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 10th percentile — 9.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.002 · change: -0.001
Affected products
- Vercel Next.js — versions >= 12.2.0, < 15.5.16, >= 16.0.0, < 16.2.5
Weakness classification (CWE)
References
- github.com/vercel/next.js/security/advisories/GHSA-3g8h-86w9-wvmq (Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-44572?
- CVE-2026-44572 is a low-severity vulnerability in Vercel Next.js, classified under CWE-349. CVSS score: 3.7/10. Published 2026-05-13.
- How severe is CVE-2026-44572?
- Low severity. CVSS v3 base score is 3.7 out of 10.