CVE-2025-20152
📋 TL;DR
An unauthenticated remote attacker can send specially crafted RADIUS authentication requests to cause Cisco Identity Services Engine (ISE) to reload, resulting in denial of service. This affects organizations using Cisco ISE for AAA services. The vulnerability requires network access to a device that communicates with ISE for authentication.
💻 Affected Systems
- Cisco Identity Services Engine (ISE)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Sustained DoS attacks could render ISE unavailable for extended periods, disrupting all network authentication and authorization services dependent on it.
Likely Case
Intermittent service disruptions causing authentication failures for users and devices, requiring manual intervention to restart services.
If Mitigated
With proper network segmentation and monitoring, impact is limited to brief service interruptions that can be quickly detected and addressed.
🎯 Exploit Status
Exploitation requires sending specific RADIUS authentication requests to a network access device that communicates with ISE.
🛠️ 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-ise-restart-ss-uf986G2Q
Restart Required: Yes
Instructions:
1. Review Cisco advisory for affected versions. 2. Download and apply appropriate patch from Cisco Software Center. 3. Schedule maintenance window for ISE restart. 4. Verify patch application and service restoration.
🔧 Temporary Workarounds
Network Segmentation
allRestrict RADIUS traffic to trusted network segments only
Access Control Lists
allImplement ACLs to limit RADIUS sources to authorized network access devices only
🧯 If You Can't Patch
- Implement strict network segmentation to isolate RADIUS traffic
- Deploy network monitoring and intrusion detection for anomalous RADIUS traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check ISE version against affected versions listed in Cisco advisoryCheck Version:
show version (in ISE CLI)Verify Fix Applied:
Verify ISE version after patch application matches fixed version in advisory📡 Detection & Monitoring
Log Indicators:
- ISE process crashes/restarts
- RADIUS authentication failures
- System reload events
Network Indicators:
- Unusual RADIUS traffic patterns
- RADIUS requests from unexpected sources
- High volume of malformed RADIUS packets
SIEM Query:
source="ISE" AND (event_type="crash" OR event_type="restart" OR message="RADIUS.*error")