CVE-2026-20339

—

CVSS 3.1

7.5 high

EPSS

<1%p39

Published

Aug 7, 2026 (Aug 7, 2026)

Modified

Aug 11, 2026

Description

A vulnerability in the PESpin 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 PESpin files during scanning, which may result in an integer overflow. An attacker could exploit this vulnerability by submitting a crafted file that contains PESpin 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.

Weakness: CWE-190
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD CVE.org GitHub PoCs EPSS (0.5%)

In the news1 stories

Cisco Warns of Seven ClamAV Flaws, Two With Public PoCs

Cisco warns of seven ClamAV denial-of-service flaws in Secure Endpoint Connector, two with public PoCs; patches due in August.

Cisco warned that seven ClamAV denial-of-service vulnerabilities, tracked as CVE-2026-20337 through CVE-2026-20339 and CVE-2026-20345 through CVE-2026-20348, affect the Secure Endpoint Connector on Windows, macOS and Linux. Two flaws, CVE-2026-20337 (CVSS 7.5, out-of-bounds write) and CVE-2026-20338 (memory double-free), have public proof-of-concept code, but Cisco PSIRT reports no evidence of malicious exploitation. Fixes shipped in ClamAV 1.5.4, with Cisco patches due in August and no workaround available. Windows is rated high risk because ClamAV runs with elevated privileges there.

Security AffairsAug 11, 16:05 UTC · Aug 11, 2026Vulnerability CVE-2026-20337 CVE-2026-20338 CVE-2026-20339+4 CVEs