# CVE-2026-64647: Next.js: Response Body Cache Confusion with Invalid UTF-8 Request Bodies

> CVE-2026-64647: Next.js: Response Body Cache Confusion with Invalid UTF-8 Request Bodies. CVSS 5.4 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-64647
Last updated: 2026-10-24T13:10:00Z

- Published: 2026-07-27 19:11 UTC · Updated: 2026-10-24 13:10 UTC · Assigner: GitHub\_M
- CVSS: 5.4 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
- EPSS: 0.32%, 24th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-116

## 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.

## Affected vendors and products

- vercel: next.js

## Tracked companies

- [Vercel](https://rewindex.com/company/vercel.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-64647)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-64647)
- [https://github.com/vercel/next.js/commit/025bf4a5f7b47fb7758c4ebf1c931a61c451c082](https://github.com/vercel/next.js/commit/025bf4a5f7b47fb7758c4ebf1c931a61c451c082)
- [https://github.com/vercel/next.js/pull/96008](https://github.com/vercel/next.js/pull/96008)
- [https://github.com/vercel/next.js/releases/tag/v15.5.21](https://github.com/vercel/next.js/releases/tag/v15.5.21)
- [https://github.com/vercel/next.js/releases/tag/v16.2.11](https://github.com/vercel/next.js/releases/tag/v16.2.11)
- [https://github.com/vercel/next.js/security/advisories/GHSA-4633-3j49-mh5q](https://github.com/vercel/next.js/security/advisories/GHSA-4633-3j49-mh5q)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-64647 · Markdown: https://rewindex.com/cve/CVE-2026-64647.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-64647 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:14:38.563Z