CVE-2025-20235
📋 TL;DR
An unauthenticated cross-site scripting (XSS) vulnerability in Cisco Secure Firewall Management Center (FMC) web interface allows remote attackers to inject malicious scripts. This could lead to session hijacking, credential theft, or unauthorized actions when users interact with the compromised interface. All organizations using vulnerable versions of Cisco FMC are affected.
💻 Affected Systems
- Cisco Secure Firewall Management Center (FMC)
📦 What is this software?
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
Secure Firewall Management Center by Cisco
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains administrative access to the firewall management system, modifies firewall rules, exfiltrates sensitive network data, or deploys malware across the network.
Likely Case
Attacker steals administrator session cookies or credentials, leading to unauthorized access to the firewall management interface and potential network configuration changes.
If Mitigated
With proper network segmentation and access controls, impact is limited to the management interface itself without lateral movement to production systems.
🎯 Exploit Status
Exploitation requires user interaction (clicking malicious link or visiting compromised page) but no authentication needed
🛠️ 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-fmc-xss-JtNmcusP
Restart Required: No
Instructions:
1. Review Cisco advisory for affected versions. 2. Download and apply the appropriate patch from Cisco. 3. Verify the patch installation. 4. Test management interface functionality.
🔧 Temporary Workarounds
Input Validation Enhancement
allImplement additional input validation and output encoding for web interface fields
Content Security Policy
allImplement strict Content Security Policy headers to restrict script execution
🧯 If You Can't Patch
- Restrict access to FMC management interface to trusted IP addresses only using firewall rules
- Implement web application firewall (WAF) with XSS protection rules in front of the management interface
🔍 How to Verify
Check if Vulnerable:
Check Cisco advisory for affected version ranges and compare with your FMC versionCheck Version:
Log into FMC web interface and navigate to System > Updates > Version InformationVerify Fix Applied:
Verify FMC software version matches or exceeds the patched version listed in Cisco advisory📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript or script-like content in web request logs
- Multiple failed login attempts followed by successful login from same IP
- Administrative actions from unexpected user sessions
Network Indicators:
- HTTP requests containing suspicious script tags or JavaScript payloads to FMC management interface
- Unusual outbound connections from FMC management interface
SIEM Query:
source="fmc_logs" AND (http_uri="*<script>*" OR http_body="*javascript:*" OR http_referer="*malicious*" OR user_agent="*malicious*")