Answer in brief
CVE-2026-64647 records a Medium severity vulnerability in Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences. The current sources do not mark it as known exploited. The current feed maps next (npm), next (npm), next (npm), next (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps next (npm), next (npm), next (npm), next (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| nextnpm | >=13.0.0 <15.5.21 | 15.5.21 |
| nextnpm | >=16.0.0 <16.2.11 | 16.2.11 |
| nextnpm | >=13.0.0<15.5.21 | Not reported |
| nextnpm | >=16.0.0<16.2.11 | Not reported |
Published upstream
Jul 21, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Jul 23, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Aug 8, 2026
## 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.
Quoted source text, attributed separately from HOL analysis.