CVE-2026-20052
📋 TL;DR
A memory management vulnerability in Cisco Secure Firewall Threat Defense (FTD) Software's Snort 3 Detection Engine allows unauthenticated remote attackers to trigger engine restarts by sending crafted SSL packets. This causes denial of service (DoS) by disrupting traffic inspection. Organizations using affected Cisco FTD versions with Snort 3 SSL inspection enabled are vulnerable.
💻 Affected Systems
- Cisco Secure Firewall Threat Defense (FTD) Software
⚠️ 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
Repeated exploitation causes persistent Snort 3 engine restarts, leading to extended traffic inspection bypass and potential network compromise during downtime.
Likely Case
Intermittent Snort 3 restarts disrupt SSL traffic inspection, causing temporary DoS and potential security monitoring gaps.
If Mitigated
With proper network segmentation and monitoring, impact is limited to brief inspection interruptions without broader network effects.
🎯 Exploit Status
Exploitation requires sending crafted SSL packets through an established connection to trigger the memory management logic error.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.4.1 and later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3ssl-FBEKYXpH
Restart Required: Yes
Instructions:
1. Download Cisco FTD Software version 7.4.1 or later from Cisco Software Center. 2. Upload the software image to the FTD device. 3. Install the update via CLI or FMC. 4. Reboot the device to complete installation.
🔧 Temporary Workarounds
Disable Snort 3 SSL Inspection
allTemporarily disable SSL packet inspection in Snort 3 Detection Engine to prevent exploitation.
configure via Cisco FMC: Policies > Access Control > Edit Policy > SSL Policy > Disable SSL Inspection
🧯 If You Can't Patch
- Implement network segmentation to restrict SSL traffic to trusted sources only.
- Deploy additional monitoring and alerting for Snort 3 engine restart events.
🔍 How to Verify
Check if Vulnerable:
Check FTD software version via CLI: 'show version' and verify if Snort 3 SSL inspection is enabled in configuration.Check Version:
show versionVerify Fix Applied:
Confirm version is 7.4.1 or later with 'show version' and verify Snort 3 engine stability under SSL traffic.📡 Detection & Monitoring
Log Indicators:
- Snort 3 Detection Engine restart events in system logs
- Increased SSL packet parsing errors
Network Indicators:
- Unusual SSL traffic patterns triggering Snort 3 restarts
- Traffic inspection gaps during engine downtime
SIEM Query:
source="cisco_ftd" AND (event_type="snort_restart" OR message="Snort 3 engine restart")