CVE-2026-62309: CoreDNS: proxyproto plugin panics on PPv2 datagram with non-UDP transport — single 28-byte packet remote DoS

highCVSS 7.5CVE-2026-62309

CSIRTS triage

vendor: CoreDNS product: CoreDNS Denial of service

What: The proxyproto plugin panics when processing a PPv2 datagram with a non-UDP transport, leading to a denial of service.
Who is affected: Deployments of CoreDNS using the proxyproto plugin.
Urgency: Remediation is urgent due to the high severity and potential for denial of service.
Action: Update to the latest version of CoreDNS that addresses this issue.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62309

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-623090.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 30% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-62309	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

highCVE-2026-62309: CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can cras…nvd

Recent advisories for CoreDNS

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEW] [medium] CoreDNS: Multiple vulnerabilities allow Denial of Servicecert-bund · 2026-07-17
lowCVE-2026-62994: CoreDNS is a DNS server written in Go. From 1.9.4 until 1.14.5, a network DNS client allowed t…nvd · 2026-07-16
highCVE-2026-62309: CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can cras…nvd · 2026-07-16
mediumCVE-2026-62299: CoreDNS is a DNS server written in Go. Prior to 1.14.5, the CoreDNS rewrite plugin supports ed…nvd · 2026-07-16
lowCVE-2026-62994: CoreDNS `k8s_external` headless AXFR can emit an empty transfer batch that panics the `transfe…msrc · 2026-07-14
mediumCVE-2026-62299: CoreDNS: rewrite-plugin EDNS0 response-revert nil-pointer panic (remote DoS) when a downstream…msrc · 2026-07-14