CVE-2026-62309 CoreDNS: proxyproto plugin panics on PPv2 datagram with non-UDP transport — single 28-byte packet remote DoS
Remote attackers can crash CoreDNS via a single UDP packet if the proxyproto plugin is enabled, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62309?
CVE-2026-62309 is a high-severity vulnerability in coredns, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can crash the CoreDNS process when the proxyproto plugin is enabled because plugin/pkg/proxyproto/proxyproto.go PacketConn.ReadFrom handles a PROXY v2 header with non-UDP transport such as family byte 0x11, reassigns addr from a nil readFrom result after parseProxyProtocol errors, and calls addr.String() in the warning log before ServeDNS recovery applies. This issue is fixed in version 1.14.4.
Weakness: CWE-476
Which versions are affected by CVE-2026-62309?
It affects 1 product.
Products include Coredns.io Coredns.
How do I fix CVE-2026-62309?
No fix has been published for CVE-2026-62309 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-62309 being exploited?
There is no known exploitation of CVE-2026-62309 in the wild and no public exploit code.
Other vulnerabilities in coredns
- CVE-2026-32934 CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service
- CVE-2026-32936 CoreDNS DoH GET path missing size validation causes CPU and memory amplification
- CVE-2026-33190 CoreDNS TSIG authentication bypass on encrypted DNS transports
- CVE-2026-33489 CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison
- CVE-2026-35579 CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports
Sources
Also known as GHSA-9rvv-m5g5-wc8r.