Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Vercel | Next.Js | >= 13.0.0, < 15.5.21 |
Related Weaknesses (CWE)
References
- https://github.com/vercel/next.js/commit/025bf4a5f7b47fb7758c4ebf1c931a61c451c08Patch
- https://github.com/vercel/next.js/pull/96008Issue TrackingPatch
- https://github.com/vercel/next.js/releases/tag/v15.5.21ProductRelease Notes
- https://github.com/vercel/next.js/releases/tag/v16.2.11ProductRelease Notes
- https://github.com/vercel/next.js/security/advisories/GHSA-4633-3j49-mh5qVendor Advisory
FAQ
What is CVE-2026-64647?
CVE-2026-64647 is a vulnerability with a CVSS score of 5.4 (MEDIUM). 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 respon...
How severe is CVE-2026-64647?
CVE-2026-64647 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-64647?
Check the references section above for vendor advisories and patch information. Affected products include: Vercel Next.Js.