An error in the EDNS Client Subnet (ECS) feature for recursive resolvers can cause BIND to exit with an assertion failure when processing a response that has malformed RRSIGs. Versions affected: BIND 9.10.5-S1 -> 9.11.6-S1 of BIND 9 Supported Preview Edition.
https://support.f5.com/csp/article/K39751401?utm_source=f5support&%3Butm_medium=RSS