Next.js: Cache confusion of response bodies for requests with bodies

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-64648: 0.34% estimated exploitation activity in the next 30 days; percentile 27.27 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 only applies to fetch calls with a request that has a different init than the one passed to fetch. Safe: fetch(new Request(init), init) Unsafe: fetch(new Request(init), aDifferentInit) Workarounds No workaround exists besides upgrading. Applications using Pages Router are not vulnerable.

Published by the source

22 Jul 2026, 23:08 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:58 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-68g3-v927-f742

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-68g3-v927-f742

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# Patch Next advisory brief: CVE-2026-64648

Advisory: Next.js: Cache confusion of response bodies for requests with bodies
IDs: CVE-2026-64648, GHSA-68g3-v927-f742
Record: https://patchnext.com/advisories/cve-2026-64648 (revision 3, source checked 26 Oct 2026, 12:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: next 16.2.11, 15.5.21. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm next: affected >= 13.0.0, < 15.5.21; >= 16.0.0, < 16.2.11; fixed in 15.5.21, 16.2.11

## Suggested inspection (read-only)
- `npm ls next --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on next.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-68g3-v927-f742 (OSV record GHSA-68g3-v927-f742 lists affected ranges: npm next >=13.0.0 =16.0.0 <16.2.11 (fixed))
- Verified: https://github.com/advisories/GHSA-68g3-v927-f742 (GitHub-reviewed advisory GHSA-68g3-v927-f742 lists affected ranges: npm next >=13.0.0 =16.0.0 <16.2.11)

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