http-cache-semantics max-stale handling can disclose cross-user cached responses

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-93748: 0.57% estimated exploitation activity in the next 30 days; percentile 47.18 (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.

http-cache-semantics through 4.2.0 fails to properly validate security-zeroed cache entries when processing client max-stale directives, allowing unauthenticated attackers to retrieve cached responses belonging to other users. Attackers can request the same URL with a large max-stale value to obtain another user's Set-Cookie session credentials from shared-cache entries that were deliberately zeroed for security reasons.

Published by the source

18 Sep 2026, 18:31 UTC

Last modified by the source

2 Oct 2026, 22:45 UTC

Source last checked

28 Oct 2026, 22:00 UTC

1. Revision 5 · withdrawn · 28 Oct 2026

   Withdrawn upstream: ghsa record GHSA-ch52-4w7c-c8xp

2. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-ch52-4w7c-c8xp

3. Revision 3 · amended · 24 Oct 2026

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

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-ch52-4w7c-c8xp

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-ch52-4w7c-c8xp

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# Patch Next advisory brief: CVE-2026-93748

Advisory: http-cache-semantics max-stale handling can disclose cross-user cached responses
IDs: CVE-2026-93748, GHSA-ch52-4w7c-c8xp
Record: https://patchnext.com/advisories/cve-2026-93748 (revision 5, source checked 28 Oct 2026, 22:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.
Status: WITHDRAWN upstream. Do not act on this record without new evidence.

## Affected components
- npm http-cache-semantics: affected <= 4.2.0

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on http-cache-semantics.
- 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://github.com/advisories/GHSA-ch52-4w7c-c8xp (GitHub-reviewed advisory GHSA-ch52-4w7c-c8xp lists affected ranges: npm http-cache-semantics >=0 <=4.2.0)
- Verified: https://osv.dev/vulnerability/GHSA-ch52-4w7c-c8xp (OSV record GHSA-ch52-4w7c-c8xp lists affected ranges: npm http-cache-semantics >=0 <=4.2.0)
- Verified: https://github.com/advisories/GHSA-ch52-4w7c-c8xp (ghsa record GHSA-ch52-4w7c-c8xp is marked withdrawn upstream (as of 2026-10-28T21:13:39Z).)

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