# CVE-2026-62309: CoreDNS NULL pointer dereference in proxyproto plugin

Source: https://junglewise.ai/threats/cve-2026-62309-coredns-null-pointer-dereference-in-proxyproto-plugin  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-16. Updated: 2026-07-16  
License: CC BY 4.0 with a link back

CVE-2026-62309 · Severity: high · CVSS 7.5 · Published 2026-07-16

CoreDNS is a widely used DNS server that translates human-readable domain names into IP addresses. A vulnerability in its 'proxyproto' plugin allows a remote attacker to crash the server by sending a single, specially crafted 28-byte network packet. This results in a complete service outage, preventing users and applications from resolving domain names until the server is manually restarted or recovered.

Technologies: [CoreDNS](https://junglewise.ai/threats/technologies/coredns). Vendors: [CoreDNS](https://junglewise.ai/threats/vendors/coredns).

## Quick answers

**Is CVE-2026-62309 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-62309 being exploited in the wild.

**How severe is CVE-2026-62309?** High severity, with a CVSS score of 7.5, published 16 July 2026.

**Which products and versions are affected?** CoreDNS < 1.14.4.

**Is there a fix for CVE-2026-62309?** A patch was published on 2026-06-08: Fix merged into master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-62309 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-62309?** Check whether you run CoreDNS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A NULL pointer dereference exists in the proxyproto plugin of CoreDNS when handling PROXY v2 headers over UDP. Specifically, in `plugin/pkg/proxyproto/proxyproto.go`, the `PacketConn.ReadFrom` function fails to properly validate the return values from `parseProxyProtocol`. When a malformed PROXY v2 header (e.g., specifying a non-UDP transport family like 0x11) is received, the parser returns a nil address and an error. The code subsequently attempts to call `.String()` on this nil address object during a logging operation before the standard recovery middleware can intercept the panic. This results in a process exit (SIGSEGV). An unauthenticated remote attacker can trigger this with a single 28-byte UDP packet. The issue is resolved in version 1.14.4.

## Affected products

- CoreDNS CoreDNS < 1.14.4

## Timeline

- 2026-05-24: other: Initial vulnerability report
- 2026-06-08: patched: Fix merged into master branch
- 2026-06-09: advisory: Version 1.14.4 released
- 2026-07-16: disclosed: CVE-2026-62309 published

## References

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

## Related threats

- [CoreDNS RFC 2136 UPDATE bypass in DoH/DoQ/gRPC](https://junglewise.ai/threats/cve-2026-86003-coredns-rfc-2136-update-bypass-in-doh-doq-grpc)
- [CoreDNS unauthenticated memory exhaustion in DoH, DoQ, and DoH3](https://junglewise.ai/threats/cve-2026-82399-coredns-unauthenticated-memory-exhaustion-in-doh-doq-and-doh3)
- [CoreDNS panic in transfer plugin via k8s_external headless services](https://junglewise.ai/threats/cve-2026-62994-coredns-panic-in-transfer-plugin-via-k8s-external-headless)
- [CoreDNS NULL pointer dereference in rewrite plugin](https://junglewise.ai/threats/cve-2026-62299-coredns-null-pointer-dereference-in-rewrite-plugin)
- [CoreDNS TSIG authentication bypass in gRPC, QUIC, and DoH transports](https://junglewise.ai/threats/cve-2026-35579-coredns-tsig-authentication-bypass-in-grpc-quic-and-doh)