Bug 2496112 (CVE-2026-20243)

Summary: CVE-2026-20243 clamav: ClamAV: Denial of Service via crafted ALZ file
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: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in ClamAV's ALZ file format parser. An unauthenticated, remote attacker can exploit this vulnerability by submitting a specially crafted ALZ (Archived Link Zipped) file for scanning. This improper handling of ALZ files can lead to memory corruption, causing the ClamAV scanning process to terminate. A successful exploit results in a Denial of Service (DoS) condition on the affected software.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2496859, 2496860    
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Description OSIDB Bzimport 2026-07-01 18:03:08 UTC 
A vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition, or possibly other expanded impacts, resulting from memory corruption on an affected device.

This vulnerability is due to improper boundary checks for content in ALZ files during scanning, which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by submitting a crafted file that contains ALZ content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.