FreeBSD: VID-719f06af-e45e-11ea-95a1-c3b8167b8026 (CVE-2020-14367): chrony <= 3.5.1 data corruption through symlink vulnerability writing the pidfile

Miroslav Lichvar reports: chrony-3.5.1 [...] fixes a security issue in writing of the pidfile. When chronyd is configured to save the pidfile in a directory where the chrony user has write permissions (e.g. /var/run/chrony - the default since chrony-3.4), an attacker that compromised the chrony user account could create a symbolic link at the location of the pidfile to make chronyd starting with root privileges follow the symlink and write its process ID to a file for which the chrony user doesn't have write permissions, causing a denial of service, or data loss. This issue was reported by Matthias Gerstner of SUSE.