High severity · published Jul 1, 2026
CVE-2026-20243
ClamAV ALZ Archive Processing Denial of Service Vulnerability
7.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 47% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CS
Cisco Secure Endpoint · Cisco
7.0.5; 6.2.19; 7.3.3; 7.2.13; 6.1.5; 6.3.1; +34 more · source: vendor
CL
Clamav · Clamav
1.4.0 before 1.4.5; 1.5.0 before 1.5.3 · source: NVD
SE
Secure Endpoint · Cisco
before 1.27.2; before 1.29.0; before 8.6.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20243
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20243
Vendor Advisory
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR
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