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.

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.

This flaw in ClamAV's ALZ file parser is rated as Important as it allows an unauthenticated, remote attacker to trigger a denial of service. By submitting a specially crafted ALZ file for scanning, an attacker can cause memory corruption, leading to the termination of the ClamAV scanning process. This could disrupt services relying on ClamAV for malware detection in Red Hat environments. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. https://www.cve.org/CVERecord?id=CVE-2026-20243 https://nvd.nist.gov/vuln/detail/CVE-2026-20243 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR