CoreDNS k8s_external headless AXFR can emit an empty transfer batch that panics the transfer plugin

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2026-62994: 0.46% estimated exploitation activity in the next 30 days; percentile 39.86 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A network DNS client allowed to request AXFR for a CoreDNS zone can trigger a panic when CoreDNS is configured with k8sexternal headless-service zone transfers and Kubernetes contains a headless service endpoint with no declared ports. The built-in k8sexternal transferer can emit an empty []dns.RR batch, and the shared transfer plugin indexes records[0] without checking that the batch is non-empty. In normal CoreDNS mode the panic is recovered and returned as SERVFAIL, but repeated triggering can disrupt requests and amplify panic logging; if the debug plugin disables recovery, the same path can crash the CoreDNS process. Details plugin/transfer/transfer.go assumes that every Transferer emits only non-empty []dns.RR batches. During AXFR/IXFR response generation it indexes records[0] without checking the slice length: - plugin/transfer/transfer.go:129-131 The built-in k8sexternal transferer violates that contract for headless services whose endpoints have no declared ports.…

Published by the source

16 Oct 2026, 19:26 UTC

Last modified by the source

19 Oct 2026, 21:31 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-74w3-63xv-x9mv

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6805

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-74w3-63xv-x9mv

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# Patch Next advisory brief: CVE-2026-62994

Advisory: CoreDNS `k8s_external` headless AXFR can emit an empty transfer batch that panics the `transfer` plugin
IDs: CVE-2026-62994, GHSA-74w3-63xv-x9mv
Record: https://patchnext.com/advisories/cve-2026-62994 (revision 3, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/coredns/coredns 1.14.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/coredns/coredns: affected >= 1.9.4, <= 1.14.4; fixed in 1.14.5

## Suggested inspection (read-only)
- Go github.com/coredns/coredns: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/coredns/coredns.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6805 (OSV record GO-2026-6805 lists affected ranges: Go github.com/coredns/coredns >=1.9.4 <1.14.5 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-74w3-63xv-x9mv (OSV record GHSA-74w3-63xv-x9mv lists affected ranges: Go github.com/coredns/coredns >=1.9.4 <1.14.5 (fixed))
- Verified: https://github.com/advisories/GHSA-74w3-63xv-x9mv (GitHub-reviewed advisory GHSA-74w3-63xv-x9mv lists affected ranges: Go github.com/coredns/coredns >=1.9.4 <=1.14.4)

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