CoreDNS is a DNS server written in Go. Prior to 1.14.5, the CoreDNS rewrite plugin supports edns0 rewrite rules with an optional revert flag, and two response rules, edns0SetResponseRule and edns0ReplaceResponseRule[T] in plugin/rewrite/edns0.go, call res.IsEdns0() and immediately dereference the returned *dns.OPT without a nil check when a downstream plugin returns a response with no OPT record. A remote, unauthenticated client can send a single ordinary DNS query matching a rewrite edns0 <local|nsid|subnet> <set|append|replace> ... revert rule, causing ResponseReverter in plugin/rewrite/reverter.go to panic, return SERVFAIL, and degrade availability, or crash the CoreDNS process if the debug directive disables recovery. This issue is fixed in version 1.14.5.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:L5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LMemory Safety