CVE-2026-64647: Next.js: Response Body Cache Confusion with Invalid UTF-8 Request Bodies
Description
Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, a server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped. This is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for 삃삃 and 섄섄 in the request body would share the same cache. This issue has been fixed in versions 15.5.21 and 16.2.11.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N · CWE-116
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
vercel: next.js
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- github.com/vercel/next.js/commit/025bf4a5f7b47fb7758c4ebf1c931a61c451c082 (opens in new tab)
- github.com/vercel/next.js/pull/96008 (opens in new tab)
- github.com/vercel/next.js/releases/tag/v15.5.21 (opens in new tab)
- github.com/vercel/next.js/releases/tag/v16.2.11 (opens in new tab)
- github.com/vercel/next.js/security/advisories/GHSA-4633-3j49-mh5q (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)