Vulnerability in Vercel Next.js
CVE-2025-49826
Next.js is a React framework for building full-stack web applications. From versions 15.0.4-canary.51 to before 15.1.8, a cache poisoning bug leading to a Denial of Service (DoS) condition was found in Next.js. This issue does not impact customers hosted on Vercel. Under certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page. This issue has been addressed in version 15.1.8.
Vulnerability class: HTTP Request Smuggling
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.011 (64.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 64.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: +0.000
Affected products
- Vercel Next.js — versions >= 15.0.4-canary.51, < 15.1.8, 15.0.4
Weakness classification (CWE)
References
- github.com/vercel/next.js/security/advisories/GHSA-67rr-84xm-4c7r (Vendor Advisory)
- github.com/vercel/next.js/commit/a15b974ed707d63ad4da5b74c1441f5b7b120e93 (Patch)
- github.com/vercel/next.js/releases/tag/v15.1.8 (Release Notes)
- vercel.com/changelog/cve-2025-49826 (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-49826?
- CVE-2025-49826 is a high-severity vulnerability in Vercel Next.js, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 7.5/10. Published 2025-07-03.
- How severe is CVE-2025-49826?
- High severity. CVSS v3 base score is 7.5 out of 10.