undici vulnerable to cross-user information disclosure and parse-time crash via degenerate private cache directives

Exploitation

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

CVSS

7.4 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS

• CVE-2026-13697: 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.

Summary Two issues in undici's cache interceptor, both fixed by the same patch on lib/util/cache.js: 1. Shared-cache disclosure: Responses with malformed qualified Cache-Control: private directives such as private="" or private="," can be incorrectly stored in the default shared cache, then served to a later caller with the same cache key. 2. Parse-time crash: Mixed unqualified-and-qualified private directives in the same header (such as public, max-age=60, private, private="hdr") cause an uncaught TypeError in the cache-control parser, terminating the request. Impact Shared-cache disclosure Applications using interceptors.cache() in shared mode may cache a user-specific response and serve it to a later caller with the same cache key. This can disclose private response bodies and headers, including Set-Cookie. Required conditions: - the cache interceptor is enabled in shared mode, including the default configuration; - an upstream returns a malformed directive such as Cache-Control:…

Published by the source

3 Aug 2026, 19:19 UTC

Last modified by the source

3 Aug 2026, 19:24 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4cwx-7wf7-3272

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# Patch Next advisory brief: CVE-2026-13697

Advisory: undici vulnerable to cross-user information disclosure and parse-time crash via degenerate private cache directives
IDs: CVE-2026-13697, GHSA-4cwx-7wf7-3272
Record: https://patchnext.com/advisories/cve-2026-13697 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: undici 8.9.0, 7.29.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm undici: affected >= 7.0.0, < 7.29.0; >= 8.0.0, < 8.9.0; fixed in 8.9.0, 7.29.0

## Suggested inspection (read-only)
- `npm ls undici --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 undici.
- 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-4cwx-7wf7-3272 (GitHub-reviewed advisory GHSA-4cwx-7wf7-3272 lists affected ranges: npm undici >=7.0.0 =8.0.0 <8.9.0)

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