What’s Vulnerable › Vulnerabilities
CVE-2026-20053: Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Heap Overflow Denial of Service Vulnerability
- Severity: medium (CVSS 5.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% 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-122
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.
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: 17.9.4, 17.9.5e, 17.12.1a, 17.12.2, 17.12.3, 17.12.3a (+23)
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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