CVE-2024-20260
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to cause memory exhaustion on Cisco ASAv and FTDv virtual firewall platforms by flooding them with SSL/TLS connections. This leads to a denial of service where VPN connections slow down and eventually stop. Only virtual appliance versions of these Cisco security products are affected.
💻 Affected Systems
- Cisco Adaptive Security Virtual Appliance (ASAv)
- Cisco Secure Firewall Threat Defense Virtual (FTDv)
⚠️ 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
Complete denial of service for all SSL VPN connections, requiring manual device reload to restore functionality.
Likely Case
VPN performance degradation leading to connection failures and service disruption.
If Mitigated
Minimal impact with proper network controls and monitoring in place.
🎯 Exploit Status
Simple connection flooding attack requiring no authentication or special tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Cisco advisory for specific fixed versions
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftdvirtual-dos-MuenGnYR
Restart Required: Yes
Instructions:
1. Review Cisco advisory for fixed versions. 2. Backup configuration. 3. Upgrade to patched version. 4. Reload device.
🔧 Temporary Workarounds
Rate limiting SSL/TLS connections
allImplement network-level rate limiting for SSL/TLS connections to the vulnerable interfaces
Network segmentation
allRestrict access to management and SSL VPN interfaces to trusted networks only
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach SSL/TLS services
- Deploy DDoS protection or rate limiting in front of vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check device version against Cisco advisory and verify SSL/TLS services are enabledCheck Version:
show versionVerify Fix Applied:
Verify device is running patched version from Cisco advisory and monitor memory usage during connection attempts📡 Detection & Monitoring
Log Indicators:
- High memory usage alerts
- SSL/TLS connection spikes
- VPN connection failures
Network Indicators:
- Unusual volume of SSL/TLS handshake attempts
- Connection floods to VPN ports
SIEM Query:
source="cisco-asa" OR source="cisco-ftd" AND (memory_usage>90 OR ssl_connections>threshold)