An issue was discovered in DAViCal Andrew's Web Libraries (AWL) through 0.60. Session management does not use a sufficiently hard-to-guess session key. Anyone who can guess the microsecond time (and the incrementing session_id) can impersonate a session.
https://www.debian.org/security/2020/dsa-4660
https://usn.ubuntu.com/4539-1/
https://lists.debian.org/debian-lts-announce/2020/04/msg00011.html