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.

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.

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

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. 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

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