CVE-2026-20054
📋 TL;DR
A vulnerability in Cisco's Snort 3 VBA feature allows unauthenticated remote attackers to crash the Snort 3 Detection Engine by sending specially crafted VBA data. This affects multiple Cisco products using Snort 3, potentially causing denial-of-service conditions on affected security devices.
💻 Affected Systems
- Cisco Firepower Threat Defense (FTD)
- Cisco Secure Firewall Management Center
- Other Cisco products using Snort 3
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Persistent denial-of-service affecting network security monitoring, allowing malicious traffic to bypass detection while Snort is down.
Likely Case
Temporary service disruption requiring Snort restart, causing brief security monitoring gaps.
If Mitigated
Minimal impact with proper network segmentation and redundant security controls in place.
🎯 Exploit Status
Exploitation requires sending specifically crafted VBA data to trigger the infinite loop condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Snort 3.2.0.0 or later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-vbavuls-96UcVVed
Restart Required: Yes
Instructions:
1. Check current Snort 3 version. 2. Update to Snort 3.2.0.0 or later via Cisco support channels. 3. Restart Snort 3 Detection Engine services. 4. Verify successful update and functionality.
🔧 Temporary Workarounds
Disable VBA inspection
allTemporarily disable VBA file inspection in Snort 3 configuration to prevent exploitation
# Configuration varies by Cisco product - consult vendor documentation
Implement rate limiting
allLimit VBA traffic to reduce exploitation risk
# Use network controls to limit VBA file transmission rates
🧯 If You Can't Patch
- Implement network segmentation to limit exposure to untrusted VBA traffic
- Deploy redundant security monitoring to maintain visibility during potential outages
🔍 How to Verify
Check if Vulnerable:
Check Snort 3 version via Cisco device management interface or CLI commands specific to your Cisco productCheck Version:
# Command varies by Cisco product - typically 'show version' or product-specific version commandsVerify Fix Applied:
Verify Snort 3 version is 3.2.0.0 or later and test with known safe VBA traffic📡 Detection & Monitoring
Log Indicators:
- Snort 3 process crashes/restarts
- High CPU usage followed by service termination
- VBA processing errors in security logs
Network Indicators:
- Unusual VBA file patterns in network traffic
- Repeated VBA transmission attempts
SIEM Query:
source="cisco_ftd" AND (event_type="process_crash" OR message="Snort 3") AND (message="VBA" OR message="decompression")