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Vulnerability · Published Jul 1, 2026 · Assigned by cisco

CVE-2026-20243ClamAV ALZ Archive Processing Denial of Service Vulnerability

High 7.5

In plain English

A high-severity buffer overflow in Cisco Secure Endpoint from Cisco. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 52.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.24clamav1.4.5-r0ALPINE-CVE-2026-20243
Debian:12clamav1.4.6+dfsg-0+deb12u1DEBIAN-CVE-2026-20243
Debian:13clamavno fix listedDEBIAN-CVE-2026-20243
Debian:14clamav1.4.5+dfsg-1DEBIAN-CVE-2026-20243
Ubuntu:22.04:LTSclamav1.5.3+dfsg-0ubuntu0.22.04.2USN-8517-1
Ubuntu:22.04:LTSclamav1.5.3+dfsg-0ubuntu0.22.04.2UBUNTU-CVE-2026-20243
Ubuntu:24.04:LTSclamav1.5.3+dfsg-0ubuntu0.24.04.1USN-8517-1
Ubuntu:24.04:LTSclamav1.5.3+dfsg-0ubuntu0.24.04.1UBUNTU-CVE-2026-20243
Ubuntu:25.10clamavno fix listedUBUNTU-CVE-2026-20243
Ubuntu:26.04:LTSclamav1.5.3+dfsg-0ubuntu0.26.04.1UBUNTU-CVE-2026-20243
Ubuntu:26.04:LTSclamav1.5.3+dfsg-0ubuntu0.26.04.1USN-8517-1

Affected products (as reported)

VendorProductVersions
Cisco Cisco Secure Endpoint 7.0.56.2.197.3.37.2.136.1.56.3.16.2.57.3.5

Weakness: CWE-120 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References