CVE-2026-20057 Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Denial of Service Vulnerability
Remote attackers can crash the Snort 3 Detection Engine by sending crafted VBA data, causing a denial of service on Cisco firewall products.
- 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-2026-20057?
CVE-2026-20057 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 a vulnerability in the Snort 3 Visual Basic for Applications (VBA) feature which could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. This vulnerability is due to lack of proper error checking when decompressing VBA data. An attacker could exploit this vulnerability by sending a 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 a denial of service (DoS) condition.
Weakness: CWE-369
Which versions are affected by CVE-2026-20057?
It affects 4 products.
Products include Cisco Cyber Vision, Cisco Secure Firewall Threat Defense, Cisco Snort, Cisco Unified Threat Defense Snort Intrusion Prevention System Engine.
How do I fix CVE-2026-20057?
No fix has been published for CVE-2026-20057 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-2026-20057 being exploited?
There is no known exploitation of CVE-2026-20057 in the wild and no public exploit code.
Other vulnerabilities in Cisco Secure Firewall Threat Defense
- CVE-2022-20685 Multiple Cisco Products Snort Modbus Denial of Service Vulnerability
- CVE-2026-20005 Denial of service in Cisco Cyber Vision
- CVE-2026-20053 Memory corruption in Cisco Cyber Vision
- CVE-2026-20054 Denial of service in Cisco Cyber Vision
- CVE-2026-20067 Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability
Sources
Also known as GHSA-3fxq-cwj2-m4x3.