LibVNC before commit 502821828ed00b4a2c4bef90683d0fd88ce495de contains heap out-of-bound write vulnerability in server code of file transfer extension that can result remote code execution
https://www.debian.org/security/2019/dsa-4383
https://usn.ubuntu.com/4587-1/
https://usn.ubuntu.com/4547-1/
https://usn.ubuntu.com/3877-1/
https://lists.debian.org/debian-lts-announce/2019/10/msg00042.html
https://lists.debian.org/debian-lts-announce/2018/12/msg00017.html