BIND versions 9.12.0 and 9.12.1 are vulnerable to problematic interaction between the serve-stale feature and NSEC aggressive negative caching can in some cases cause undesirable behavior from named, such as a recursion loop or an assertion failure resulting in termination of the named process. Deliberate exploitation of this condition could cause operational problems depending on the particular manifestation -- either degradation or denial of service.
Statement: This security flaw only affects bind versions 9.12.0 and 9.12.1. Since Red Hat Enterprise Linux does not ship any of these bind versions, it is not affected.
External Reference: https://kb.isc.org/article/AA-01606/74/CVE-2018-5737 Upstream Patch: https://ftp.isc.org/isc/bind9/9.12.1-P2/patches/cve5737.patch