CVE-2026-20058 Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Denial of Service Vulnerability

Medium 5.8 Published 4 Mar 2026 Updated 4 Mar 2026

Remote attackers can crash the Snort 3 Detection Engine by sending crafted VBA data, causing a denial of service on Cisco Secure Firewall Threat Defense devices.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-20058?

CVE-2026-20058 is a medium-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Multiple Cisco products are affected by vulnerabilities in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. These vulnerabilities are due to improper error checking when decompressing VBA data. An attacker could exploit these vulnerabilities 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 unexpectedly restart, causing a DoS condition.

Weakness: CWE-786

Which versions are affected by CVE-2026-20058?

It affects 3 products.

Products include Cisco Secure Firewall Threat Defense, Cisco Snort, Cisco Unified Threat Defense Snort Intrusion Prevention System Engine.

How do I fix CVE-2026-20058?

No fix has been published for CVE-2026-20058 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-20058 being exploited?

There is no known exploitation of CVE-2026-20058 in the wild and no public exploit code.

All Cisco Secure Firewall Threat Defense vulnerabilities

Sources

Also known as GHSA-q3px-v248-7pc3.