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.
{ "urgency": "not yet assigned" }
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2011-4407.json"