PYSEC-2023-228

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.