Bug 2466859 (CVE-2026-33489)

Summary:	CVE-2026-33489 CoreDNS: github.com/coredns/coredns: CoreDNS: Information disclosure via incorrect ACL stanza selection in transfer plugin
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	alcohan, gparvin, jbalunas, pahickey, rhaigner
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in CoreDNS. An unauthorized remote client can exploit a vulnerability in the transfer plugin's Access Control List (ACL) stanza selection. This occurs when both a parent zone and a more-specific subzone are configured, and the longestMatch() function incorrectly uses a lexicographic string comparison. As a result, a permissive parent-zone transfer rule can override a restrictive subzone rule, allowing the client to perform zone transfers (AXFR/IXFR) for the subzone and retrieve its full zone contents. This leads to the disclosure of sensitive information.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-05-05 20:01:46 UTC

CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the transfer plugin can select the wrong ACL stanza when both a parent zone and a more-specific subzone are configured. The longestMatch() function in plugin/transfer/transfer.go uses a lexicographic string comparison instead of an actual longest-suffix match to select the winning zone. As a result, a permissive parent-zone transfer rule can override a restrictive subzone rule depending on zone name ordering (e.g., "example.org." > "a.example.org." lexicographically). This allows an unauthorized remote client to perform AXFR/IXFR for the subzone and retrieve its full zone contents. This issue has been fixed in version 1.14.3.