CVE intelligence

CVE-2026-20347

Vulnerability intelligence

Published Aug 7, 2026Sources checked Oct 28, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-20347 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Aug 23, 2026

CBL-Mariner Releases

Vendor-listed releases

1.5.4-1

Cisco Security Advisories guidance

Vendor revision: Aug 13, 2026

Cisco has released software updates that address these vulnerabilities in affected Cisco platforms.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.6%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-20347?

A vulnerability in the Mach-O 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 Mach-O files during scanning, which may result in an out-of-bounds buffer read. An attacker could exploit this vulnerability by submitting a crafted Mach-O file 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.

Source: NVD