CVE-2026-26017

Name of the Vulnerable Software and Affected Versions CoreDNS versions prior to 1.14.2

Description A logical flaw exists due to the default execution order of plugins, where security plugins such as acl are evaluated before the rewrite plugin. This creates a Time-of-Check Time-of-Use (TOCTOU) flaw—a race condition where a resource is checked but then modified before it is used—allowing attackers to bypass DNS access controls. In multi-tenant Kubernetes clusters, this can undermine DNS-based segmentation, enabling unauthorized service discovery and reconnaissance of restricted internal infrastructure by mapping public names to internal services after the access control check has passed.

Recommendations Update to version 1.14.2. Reorder the default plugin.cfg so that rewrite and other normalization plugins run before acl, opa, and firewall. Ensure all access control checks are applied after name normalization.