Pip maintainers vulnerabilities and threats

CVE-2026-6357 is a medium severity vulnerability in pip versions prior to 26.1. The issue involves pip running its self-update check after installing wheel files, which requires importing well-known Python modules. This import was deferred to improve startup time but could lead to unintended module imports shortly after installation. The patch changes the self-update check to run before wheel installation to prevent this behavior. Users are advised to review package contents before installation. No known exploits are reported, and no official patch or remediation level is explicitly stated in the advisory.

When installing a package from a Mercurial VCS URL (ie "pip install hg+...") with pip prior to v23.3, the specified Mercurial revision could be used to inject arbitrary configuration options to the "hg clone" call (ie "--config"). Controlling the Mercurial configuration can modify how and which repository is installed. This vulnerability does not affect users who aren't installing from Mercurial.