CVE-2026-20348 Cisco CVE debrief

Who should care

Organizations using Cisco Secure Endpoint, particularly those with installations on macOS, Linux, and Windows platforms, should be aware of this vulnerability. The vulnerability affects Cisco Secure Endpoint versions prior to 1.27.4 on macOS, 1.29.2 on Linux, 7.5.24.21780 on Windows, and 8.6.3 on Windows 8.0 and later. IT administrators, cybersecurity teams, and network security professionals responsible for managing and securing Cisco Secure Endpoint installations should prioritize patching and mitigation efforts.

Technical summary

A vulnerability in the XAR file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device. This vulnerability is due to improper boundary checks for content in XAR files during scanning. An attacker could exploit this vulnerability by submitting a crafted file that contains XAR 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.

Defensive priority

High-priority defensive actions are required to address this vulnerability, as it could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts due to memory corruption on an affected device.

Recommended defensive actions

• Inventory and assess Cisco Secure Endpoint installations for potential exposure, focusing on versions prior to 1.27.4 on macOS, 1.29.2 on Linux, 7.5.24.21780 on Windows, and 8.6.3 on Windows 8.0 and later.
• Apply vendor-recommended patches or updates for ClamAV XAR file format parsing as soon as available.
• Implement compensating controls such as network segmentation, traffic monitoring, and filtering to reduce exposure.
• Enhance monitoring and exception tracking for ClamAV scanning processes and system performance.
• Consider temporary workarounds like disabling XAR file scanning until a patch is applied.

Evidence notes

The vulnerability is due to improper boundary checks for content in XAR files during scanning. An attacker could exploit this vulnerability by submitting a crafted file that contains XAR content to be scanned by ClamAV on an affected device. Evidence is based on official CVE and NVD records, as well as a vendor advisory.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.