CoreDNS is a DNS server written in Go. Prior to 1.14.7, the DNS-over-HTTPS, DNS-over-HTTP/3, DNS-over-QUIC, and DNS-over-gRPC request paths in plugin/pkg/doh/doh.go, core/dnsserver/server_quic.go, and core/dnsserver/server_grpc.go call dns.Msg.Unpack on attacker-controlled DNS section counts before dns.DefaultMsgAcceptFunc validates the fixed header. An unauthenticated client can use DNS name compression and excessive section counts to amplify allocation before the plugin chain, so plugin-level rate limiting cannot prevent concurrent requests from exhausting memory and terminating CoreDNS.
The ordinary UDP and TCP listeners are not affected because they validate the header first. This issue is fixed in version 1.14.7.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/coredns/coredns/commit/530b0a5ff2ad68cc0421f10dd93568945cc67…
security-advisories@github.com
https://github.com/coredns/coredns/releases/tag/v1.14.7
security-advisories@github.com
https://github.com/coredns/coredns/security/advisories/GHSA-mrg3-qvqr-jw29
security-advisories@github.com