Cisco has issued a warning about multiple vulnerabilities in ClamAV that could disrupt file scans on affected Cisco Secure Endpoint Connector installations This article explores vulnerabilities clamav. . These flaws, identified in advisory cisco-sa-clamav-WuuvVd26, affect Windows, Linux, and macOS endpoints using the ClamAV engine to inspect files.
Cisco assigned a High impact rating and a CVSS base score of 7.5 to affected Windows connectors, noting that this reflects the privileged context in which the scanning process operates. ClamAV Memory Corruption Bugs Linux and macOS connectors were rated Medium due to their scanning processes running with lower privileges. A malicious object only requires reaching a path monitored by the connector, such as email delivery, downloads, shared storage, web transfers, or automated file ingestion.
CVE-2026-20337 is an out-of-bounds write in the ZIP archive parser, caused by insufficient boundary checks during ClamAV's processing of archive content. The advisory does not claim confirmed remote code execution, yet endpoint security teams should treat malformed documents and archives as risks, especially in scenarios where scanning availability is crucial for prevention. Adversaries could use crafted files to cause repeated failures, reducing visibility and forcing defenders to investigate apparent reliability issues quickly.
Organizations must ensure compatibility by verifying connector versions, policies, and rollout statuses. Administrators should prioritize Windows systems, confirm automatic connector updates are enabled, and quickly deploy fixed releases once they become available.
