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

> Remote attackers can crash CoreDNS via a single UDP packet if the proxyproto plugin is enabled, causing denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jul 2026
- **Updated:** 18 Jul 2026
- **Also known as:** GHSA-9rvv-m5g5-wc8r

## What is CVE-2026-62309?

CVE-2026-62309 is a high-severity vulnerability in coredns, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-62309?

It affects 1 product.


Products: Coredns.io Coredns.

## How do I fix CVE-2026-62309?

No fix has been published for CVE-2026-62309 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-62309 being exploited?

There is no known exploitation of CVE-2026-62309 in the wild and no public exploit code.

## Other vulnerabilities in coredns

- [CVE-2026-32934](https://insights.sbomify.com/CVE-2026-32934/): CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service (high 8.7)
- [CVE-2026-32936](https://insights.sbomify.com/CVE-2026-32936/): CoreDNS DoH GET path missing size validation causes CPU and memory amplification (high 8.7)
- [CVE-2026-33190](https://insights.sbomify.com/CVE-2026-33190/): CoreDNS TSIG authentication bypass on encrypted DNS transports (high 8.7)
- [CVE-2026-33489](https://insights.sbomify.com/CVE-2026-33489/): CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison (high 8.2)
- [CVE-2026-35579](https://insights.sbomify.com/CVE-2026-35579/): CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62309 and fix it if it is affected.

What it is: CVE-2026-62309 is a high-severity vulnerability in coredns, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-62309 in the wild and no public exploit code.

Affected product: coredns. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-62309/ (Markdown: https://insights.sbomify.com/CVE-2026-62309/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62309
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62309
- OSV: https://osv.dev/vulnerability/CVE-2026-62309

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-62309/
Summaries are generated and may contain mistakes; the official description above is the record.