Feed/CVE-2026-64647
CVE-2026-64647MEDIUMCVSS 5.4

Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences

Published Jul 22, 2026·Updated Jul 29, 2026

NVD Description

## Impact 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. ## Workarounds If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). Applications using Pages Router are not vulnerable.

Affected Packages (1)

nextNPM
From 13.0.0
Fixed in 15.5.21

References

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