More information about this security flaw is available in the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=2371272 Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
I've verified that there is no way to exploit the vulnerability in the bundled requests library via any calls to pip. The vulnerable function (fixed in https://github.com/psf/requests/commit/96ba401c1296ab1dda74a2365ef36d88f7d144ef) is there, but it is never used because pip has the logic for loading usernames and passwords from netrc files implemented in MultiDomainBasicAuth class (in _internal/network/auth.py or download.py in older releases of pip).