CVE-2026-20243
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk31th percentile — higher than 31% of all known CVEs
Summary
A vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or other impacts due to memory corruption. The issue stems from improper boundary checks during ALZ file scanning, leading to an out-of-bounds buffer write.
Risk Assessment
An attacker can submit a crafted ALZ file, causing the ClamAV scanning process to terminate, resulting in a denial of service (DoS) and potentially other severe consequences for the affected system.
Recommendation
Immediately update ClamAV to a patched version addressing CVE-2026-20243 and implement controls to limit processing of untrusted ALZ files.
Original NVD description (English source)
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.