Bug 2568790 (CVE-2026-123586)

Summary: CVE-2026-123586 hickory-resolver: hickory-resolver: Denial of Service via cyclic DNS referrals
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: dbosanac, jcantril, jlanda, jreimann, kshier, mdessi, mrizzi, pcattana, rbobbitt, rhel-process-autobot, rojacob, simaishi, stcannon, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in hickory-resolver. This vulnerability allows a remote attacker to cause a Denial of Service (DoS) through query amplification. By controlling two domain zones whose name servers cyclically reference each other without address records (glue records), an attacker can cause the recursive resolver to enter a loop, generating excessive upstream queries and consuming system and network resources.
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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 2026-11-08 02:06:15 UTC
Hickory DNS 0.25.0-alpha.3 through 0.25.2 contains a query amplification vulnerability in its recursive resolver, which mishandles cyclic sibling name server referrals that lack glue records. Attackers controlling two zones whose name servers reference each other without glue records can make the recursor loop, sending many upstream queries, amplified further by zero-TTL NS records.