Bug 2503060 (CVE-2026-32665)

Summary: CVE-2026-32665 unbound: Unbound: Denial of Service via improper validation of DNS-over-QUIC client length
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: rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in Unbound when DNS-over-QUIC (DoQ) is enabled. An attacker could exploit improper validation of client-provided data length, leading to excessive memory allocation. This can cause the system to exceed its configured memory limits for QUIC connections, resulting in a Denial of Service (DoS) for new DoQ clients.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2507651    
Bug Blocks:    
Deadline: 2026-07-22   

Description OSIDB Bzimport 2026-07-20 21:10:12 UTC
When downstream DNS-over-QUIC (DoQ) is enabled, Unbound documents the 'quic-size' configuration option as the maximum number of bytes for all QUIC buffers and data combined, and states that new connections or streams should be refused/reset once the limit is exceeded. However, an improper validation of the client provided length could allow over allocating memory and trivially exceeding the configured budget for future DoQ connections leading to denial of service for new DoQ clients.