A flaw in query-handling code can cause named to exit prematurely with an assertion failure when:
nxdomain-redirect <domain>; is configured, and
the resolver receives a PTR query for an RFC 1918 address that would normally result in an authoritative NXDOMAIN response.
This issue affects BIND 9 versions 9.12.0 through 9.16.45, 9.18.0 through 9.18.21, 9.19.0 through 9.19.19, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.