CVE-2026-20053

Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Heap Overflow Denial of Service Vulnerability

MEDIUM

5.8

CVSS Score

Published: March 4, 2026 at 05:46 PM UTC

Updated: August 20, 2026 at 03:45 PM UTC

4 products affected across 1 vendorSecure Firewall Threat DefenseUnified Threat Defense Snort Intrusion Prevention System EngineCisco Cyber Vision

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Severity

MEDIUM5.8

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

Multiple Cisco products are affected by a vulnerability in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. This vulnerability is due to improper range checking when decompressing VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause an overflow of heap data, which could cause a DoS condition.