CVE-2026-20065
📋 TL;DR
A vulnerability in Cisco's Snort 3 Detection Engine allows unauthenticated remote attackers to trigger a restart of the engine by sending specially crafted packets through established connections. This causes a denial-of-service condition by interrupting packet inspection. Affected systems include multiple Cisco products using vulnerable versions of Snort 3.
💻 Affected Systems
- Cisco Firepower Threat Defense (FTD)
- Cisco Secure Firewall Management Center
- Cisco Secure Firewall 3100 Series
- Cisco Secure Firewall 4200 Series
- 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 exploitation could cause repeated Snort 3 restarts, leading to sustained packet inspection disruption and potential network security bypass during downtime.
Likely Case
Intermittent Snort 3 restarts causing temporary packet inspection gaps and potential security monitoring blind spots.
If Mitigated
Brief inspection interruption with minimal impact if proper network segmentation and redundancy are in place.
🎯 Exploit Status
Exploitation requires sending packets through established connections, but no authentication is needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Snort 3 version 3.1.58.0 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 following Cisco's upgrade procedures. 4. Restart affected services/systems.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to Snort 3 systems to minimize exposure to potential attackers.
Connection Rate Limiting
allImplement rate limiting on connections to reduce potential exploitation attempts.
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure to trusted sources only.
- Monitor Snort 3 process restarts and implement alerting for abnormal restart patterns.
🔍 How to Verify
Check if Vulnerable:
Check Snort 3 version with 'snort -V' or through Cisco management interface. Versions below 3.1.58.0 are vulnerable.Check Version:
snort -V | grep 'Version'Verify Fix Applied:
Verify Snort 3 version is 3.1.58.0 or higher after patching and monitor for abnormal restarts.📡 Detection & Monitoring
Log Indicators:
- Unexpected Snort 3 process restarts
- Detection engine restart messages in system logs
- Increased restart frequency in monitoring
Network Indicators:
- Unusual packet patterns targeting Snort 3 systems
- Increased connection attempts to Snort 3 ports
SIEM Query:
source="snort.log" AND ("restart" OR "unexpected termination" OR "engine stopped")