Unbound before 1.9.4 accesses uninitialized memory, which allows remote attackers to trigger a crash via a crafted NOTIFY query. The source IP address of the query must match an access-control rule.
github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/E65NCWZZB2D75ZIYWPXKMVGSGNYW4JMC/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MLRHE7TQFAOV4MB2ELTOGESZYUL65NUJ/
nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
seclists.org/bugtraq/2019/Oct/23
usn.ubuntu.com/4149-1/
www.debian.org/security/2019/dsa-4544