CoreDNS' transfer stanza selection uses lexicographic compare (subzone ACL bypass)

Exploitation

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

CVSS 4.0

8.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-33489: 0.40% estimated exploitation activity in the next 30 days; percentile 34.72 (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 CoreDNS' transfer plugin can select the wrong ACL stanza when both a parent zone and a more-specific subzone are configured. A permissive parent-zone transfer rule can override a restrictive subzone rule (name-dependent), allowing an unauthorized client to perform AXFR/IXFR for the subzone and retrieve its zone contents. Details In plugin/transfer/transfer.go, stanza selection is implemented by longestMatch(), which is documented as "longest zone match wins", but it actually chooses the winner via a lexicographic string comparison: - zone := "" // longest zone match wins (plugin/transfer/transfer.go) - if z zone { zone = z; x = xfr } (plugin/transfer/transfer.go) So, a parent zone like example.org. can beat a child zone like a.example.org. purely due to lexicographic ordering ("example.org." "a.example.org."), even though the child zone is the longer/more specific suffix match. The bypass is data-dependent (some child labels will win, some will lose), making it operationally…

Published by the source

28 Apr 2026, 22:44 UTC

Last modified by the source

8 May 2026, 15:28 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-h8mm-c463-wjq3

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# Patch Next advisory brief: CVE-2026-33489

Advisory: CoreDNS' transfer stanza selection uses lexicographic compare (subzone ACL bypass)
IDs: CVE-2026-33489, GHSA-h8mm-c463-wjq3
Record: https://patchnext.com/advisories/cve-2026-33489 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
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 1.14.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/coredns/coredns: affected < 1.14.3; fixed in 1.14.3

## 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://github.com/advisories/GHSA-h8mm-c463-wjq3 (GitHub-reviewed advisory GHSA-h8mm-c463-wjq3 lists affected ranges: Go github.com/coredns/coredns >=0 <1.14.3)

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