What’s Vulnerable › Vulnerabilities

CVE-2026-82399: CoreDNS: Unauthenticated memory exhaustion in custom transports

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-16 · updated 2026-09-24
• Weakness: CWE-770

Description

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.

Affected products

• coredns: before 1.14.7

References

• https://github.com/coredns/coredns/commit/530b0a5ff2ad68cc0421f10dd93568945cc671c9
• https://github.com/coredns/coredns/releases/tag/v1.14.7
• https://github.com/coredns/coredns/security/advisories/GHSA-mrg3-qvqr-jw29
• https://github.com/coredns/coredns/security/advisories/GHSA-mrg3-qvqr-jw29

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