CVE-2025-11838
📋 TL;DR
A memory corruption vulnerability in WatchGuard Fireware OS allows unauthenticated attackers to trigger Denial of Service (DoS) conditions in Mobile User VPN and Branch Office VPN when configured with dynamic gateway peers using IKEv2. This affects organizations using vulnerable WatchGuard firewalls with specific VPN configurations. The vulnerability can cause service disruption without requiring authentication.
💻 Affected Systems
- WatchGuard Firebox appliances running Fireware OS
📦 What is this software?
Fireware by Watchguard
Fireware by Watchguard
⚠️ Risk & Real-World Impact
Worst Case
Complete disruption of VPN services, preventing remote users and branch offices from accessing network resources, potentially leading to business interruption.
Likely Case
Intermittent VPN service outages affecting mobile users and branch office connectivity, requiring firewall reboots to restore service.
If Mitigated
Limited impact with proper network segmentation and monitoring, allowing quick detection and response to DoS attempts.
🎯 Exploit Status
The vulnerability requires no authentication and affects specific VPN configurations, making exploitation straightforward for attackers who can reach the vulnerable services.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fireware OS 12.11.5 and 2025.1.3
Vendor Advisory: https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2025-00018
Restart Required: Yes
Instructions:
1. Download the appropriate firmware update from WatchGuard Support. 2. Backup current configuration. 3. Apply firmware update through Web UI or CLI. 4. Reboot the firewall. 5. Verify the update was successful.
🔧 Temporary Workarounds
Disable vulnerable VPN configurations
allTemporarily disable Mobile User VPN with IKEv2 and Branch Office VPN with IKEv2 using dynamic gateway peers until patching can be completed.
Restrict VPN access
allImplement network access controls to limit VPN access to trusted IP addresses only.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate VPN services from untrusted networks
- Deploy intrusion prevention systems (IPS) with signatures for IKEv2 protocol anomalies
🔍 How to Verify
Check if Vulnerable:
Check Fireware OS version in Web UI (System > Status) or CLI (show version). Verify if Mobile User VPN with IKEv2 or Branch Office VPN with IKEv2 using dynamic gateway peers is configured.Check Version:
show versionVerify Fix Applied:
Confirm Fireware OS version is 12.11.5 or higher for 12.x branch, or 2025.1.3 or higher for 2025.x branch. Test VPN connectivity to ensure services remain functional.📡 Detection & Monitoring
Log Indicators:
- Multiple IKEv2 connection failures
- VPN service restart events
- Memory allocation errors in system logs
- Increased CPU usage on firewall
Network Indicators:
- Unusual IKEv2 traffic patterns
- VPN connection timeouts
- Increased retransmission rates on VPN interfaces
SIEM Query:
source="firewall" AND (event_type="vpn_failure" OR event_type="service_restart") AND protocol="ikev2"