CVE-2026-20243CWE-120

ClamAV ALZ Archive Processing Denial of Service Vulnerability

High · published July 1, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
46.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00573 · 46.6th percentile
Weakness
CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Published
2026-07-01T16:30Z
EPSS history
Timeline
  • 01 JUL 16:30Z
    ClamAV ALZ Archive Processing Denial of Service Vulnerability
    cvelistv5