Bug 2501535 (CVE-2026-62309)

Summary: CVE-2026-62309 github.com/coredns/coredns: CoreDNS: Denial of Service via crafted UDP datagram with proxyproto plugin
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, gparvin, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhaigner, sghai, sidsharm, suppawar, vlaad
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in CoreDNS. A remote attacker can send a specially crafted 28-byte UDP datagram to a CoreDNS server with the proxyproto plugin enabled. This malformed datagram can cause the CoreDNS process to crash, leading to a denial of service (DoS). The vulnerability arises from improper handling of a PROXY v2 header with a non-UDP transport type, which results in a nil pointer dereference.
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Description OSIDB Bzimport 2026-07-16 21:01:22 UTC 
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.