USN-4538-1: PackageKit vulnerabilities

Vaisha Bernard discovered that PackageKit incorrectly handled certain methods. A local attacker could use this issue to learn the MIME type of any file on the system. (CVE-2020-16121) Sami Niemimäki discovered that PackageKit incorrectly handled local deb packages. A local user could possibly use this issue to install untrusted packages, contrary to expectations. (CVE-2020-16122)