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MEDIUM5.9

PYSEC-2026-665

Mercurial Improper Certificate Validation vulnerability

Quick fix

PYSEC-2026-665 — mercurial: upgrade to the fixed version with the command below.

pip install --upgrade 'mercurial>=1.6.4'

Details

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.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/mercurial
Introduced in: 0Fixed in: 1.6.4
Fixpip install --upgrade 'mercurial>=1.6.4'

References