What’s Vulnerable › Vulnerabilities
CVE-2026-20054: Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Infinite Loop Denial of Service Vulnerability
- Severity: medium (CVSS 5.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-03-04 · updated 2026-08-20
- Weakness: CWE-835
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 error checking when decompressing VBA data. 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 the Snort 3 Detection Engine to enter an infinite loop, causing a DoS condition.
Affected products
- Cisco Cyber Vision: 3.0.0, 3.0.1, 3.0.2, 3.0.3, 3.0.4, 3.0.5 (+47)
- Cisco Firepower Threat Defense Software: 7.2.0, 7.2.0.1, 7.2.1, 7.2.2, 7.2.3, 7.2.4 (+31)
- Cisco Snort: from 3.0.0-233 before 3.9.3.0 — fixed in 3.9.3.0
- Cisco UTD SNORT IPS Engine Software: 3.17.0s, 3.17.1s, 16.6.1, 16.6.5, 16.6.6, 16.6.7a (+97)
How to fix
Upgrade to a fixed version: Cisco Snort 3.9.3.0. Check the vendor advisory for mitigations.
References
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