Bug 2568724 (CVE-2026-123585)

Summary: CVE-2026-123585 hickory-resolver: hickory-resolver: Denial of Service via DNS query amplification from irrelevant CNAME records
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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. A remote attacker controlling a malicious Domain Name System (DNS) server can cause a Denial of Service (DoS) through query amplification. By returning responses containing irrelevant Canonical Name (CNAME) records outside the requested resolution chain, an attacker induces the resolver into issuing unnecessary queries. This can lead to excessive network traffic and resource exhaustion.
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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 02:01:55 UTC
The hickory-resolver component of Hickory DNS 0.25.0 before 0.26.2 follows irrelevant CNAME records when resolving recursive queries, sending queries that are unnecessary to answer the original request. Attackers controlling DNS responses can include CNAME records in the authority or additional sections, or outside the original query name's CNAME chain, causing excess resolver queries and increased query amplification.