CVE-2025-20252
📋 TL;DR
This vulnerability in Cisco ASA and FTD software allows unauthenticated remote attackers to trigger a memory leak by sending crafted IKEv2 packets, causing denial of service that requires manual reboot. Organizations using affected Cisco firewall devices with IKEv2 VPN enabled are at risk.
💻 Affected Systems
- Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
- 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
Complete system instability requiring manual reboot, disrupting all VPN connectivity and potentially affecting firewall operations
Likely Case
Partial memory exhaustion causing inability to establish new IKEv2 VPN sessions while existing connections may remain functional
If Mitigated
Minimal impact if proper network segmentation and access controls prevent attackers from reaching IKEv2 services
🎯 Exploit Status
Exploitation requires sending continuous crafted IKEv2 packets, which is relatively straightforward for attackers with network access
🛠️ 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-asa-ftd-ios-dos-DOESHWHy
Restart Required: Yes
Instructions:
1. Review Cisco advisory for affected versions 2. Download and apply appropriate patch from Cisco 3. Schedule maintenance window for reboot 4. Verify fix after reboot
🔧 Temporary Workarounds
Restrict IKEv2 Access
cisco-asaLimit access to IKEv2 services using access control lists or firewall rules
access-list IKEV2-ACL extended permit udp <trusted-networks> host <asa-ip> eq 500
access-list IKEV2-ACL extended permit udp <trusted-networks> host <asa-ip> eq 4500
access-group IKEV2-ACL in interface outside
Disable IKEv2 if not needed
cisco-asaTemporarily disable IKEv2 VPN if alternative VPN protocols are available
crypto ikev2 enable outside client-services port 443
no crypto ikev2 enable outside
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach IKEv2 services (ports 500/4500)
- Monitor system memory usage and IKEv2 connection attempts for anomalous patterns
🔍 How to Verify
Check if Vulnerable:
Check ASA/FTD version against Cisco advisory: 'show version' and compare to affected versions listCheck Version:
show version | include VersionVerify Fix Applied:
After patching: 1. Verify version updated 2. Test IKEv2 VPN connectivity 3. Monitor memory usage during IKEv2 traffic📡 Detection & Monitoring
Log Indicators:
- High memory usage alerts
- IKEv2 connection failures
- System instability logs
- Repeated IKEv2 packet parsing errors
Network Indicators:
- Unusual volume of IKEv2 packets from single source
- Continuous IKEv2 connection attempts
- Traffic to UDP ports 500/4500 from untrusted sources
SIEM Query:
source="asa_logs" AND ("%ASA-4-733100" OR "%ASA-6-113015" OR memory_usage>90)