Next.js cache poisoning due to omission of Vary header
8Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 3.7epss 0.4%
exploitation probability
0.4%top 64% of all CVEs
observed exploitation
nono source reports it
Next.js is a React framework for building full-stack web applications. In Next.js App Router from 15.3.0 to before 15.3.3 and Vercel CLI from 41.4.1 to 42.2.0, a cache poisoning vulnerability was found. The issue allowed page requests for HTML content to return a React Server Component (RSC) payload instead under certain conditions. When deployed to Vercel, this would only impact the browser cache, and would not lead to the CDN being poisoned. When self-hosted and deployed externally, this could lead to cache poisoning if the CDN does not properly distinguish between RSC / HTML in the cache keys. This issue has been resolved in Next.js 15.3.3.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
vercel · next.jsReferences
https://github.com/vercel/next.js/commit/ec202eccf05820b60c6126d6411fe16766ecc066https://github.com/vercel/next.js/issues/79346https://github.com/vercel/next.js/releases/tag/v15.3.3https://github.com/vercel/next.js/security/advisories/GHSA-r2fc-ccr8-96c4https://vercel.com/changelog/cve-2025-49005