Canonical » Software-properties : Security Vulnerabilities, CVEs,

software-properties was vulnerable to a person-in-the-middle attack due to incorrect TLS certificate validation in softwareproperties/ppa.py. software-properties didn't check TLS certificates under python2 and only checked certificates under python3 if a valid certificate bundle was provided. Fixed in software-properties version 0.92.

ppa.py in Software Properties before 0.81.13.3 does not validate the server certificate when downloading PPA GPG key fingerprints, which allows man-in-the-middle (MITM) attackers to spoof GPG keys for a package repository.