CVE-2026-20067
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to cause a denial-of-service by sending crafted HTTP packets that trigger the Snort 3 detection engine to restart. It affects Cisco products using Snort 3 for packet inspection. The restart interrupts traffic inspection until the engine recovers.
💻 Affected Systems
- Cisco Firepower Threat Defense
- Cisco Secure Firewall Management Center
- Cisco Secure Firewall
- 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
Continuous DoS attacks could repeatedly restart Snort 3, causing extended periods of unmonitored network traffic and potential security bypass.
Likely Case
Intermittent packet inspection interruptions during attack periods, with automatic recovery after each restart.
If Mitigated
Minimal impact with proper network segmentation and monitoring; traffic continues to flow but inspection is temporarily interrupted.
🎯 Exploit Status
Exploitation requires sending crafted HTTP packets through established connections to vulnerable systems.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Snort 3 version 3.2.0.0 or later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz
Restart Required: Yes
Instructions:
1. Review Cisco advisory for specific product updates. 2. Download appropriate patches from Cisco Software Center. 3. Apply updates during maintenance window. 4. Restart affected services/systems.
🔧 Temporary Workarounds
Disable Snort 3 HTTP inspection
allTemporarily disable HTTP inspection in Snort 3 configuration to prevent exploitation
# Configuration varies by Cisco product - consult product documentation
Network segmentation
allRestrict HTTP traffic to vulnerable systems from untrusted networks
# Use firewall rules to limit HTTP access to trusted sources only
🧯 If You Can't Patch
- Implement strict network access controls to limit HTTP traffic to vulnerable systems
- Monitor for Snort 3 restart events and implement alerting for potential attacks
🔍 How to Verify
Check if Vulnerable:
Check Snort 3 version: 'snort --version' or via Cisco product management interfaceCheck Version:
snort --version | grep 'Version'Verify Fix Applied:
Verify Snort 3 version is 3.2.0.0 or higher and monitor for restart events📡 Detection & Monitoring
Log Indicators:
- Snort 3 process restart events
- Unexpected Snort 3 termination logs
- Increased restart frequency in system logs
Network Indicators:
- Unusual HTTP traffic patterns targeting Snort-protected systems
- Crafted HTTP packets with Multicast DNS fields
SIEM Query:
source="snort.log" AND ("restart" OR "terminated unexpectedly" OR "segmentation fault")