CVE-2025-45491
📋 TL;DR
This CVE describes a command injection vulnerability in Linksys E5600 routers via the DynDNS username parameter. Attackers can execute arbitrary commands with root privileges on affected devices. This affects Linksys E5600 v1.1.0.26 users who have DynDNS configured or accessible.
💻 Affected Systems
- Linksys E5600
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise allowing attacker to install persistent backdoors, intercept all network traffic, pivot to internal networks, or brick the device.
Likely Case
Remote code execution leading to router takeover, credential theft, DNS hijacking, and network surveillance.
If Mitigated
Limited impact if device is behind firewall with no external access to admin interface.
🎯 Exploit Status
Exploit script available on GitHub. Requires authentication to admin interface or access to vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Linksys support site for firmware updates
2. Download latest firmware
3. Access router admin interface
4. Navigate to firmware update section
5. Upload and apply new firmware
6. Reboot router
🔧 Temporary Workarounds
Disable DynDNS
allTurn off DynDNS functionality to remove vulnerable component
Restrict Admin Interface Access
linuxBlock external access to router admin interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace affected router with updated model
- Place router behind firewall with strict inbound rules
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under Administration > Firmware UpdateCheck Version:
curl -s http://router-ip/status.cgi | grep firmwareVerify Fix Applied:
Verify firmware version is newer than v1.1.0.26📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts to admin interface
- Suspicious DynDNS configuration changes
Network Indicators:
- Unusual outbound connections from router
- DNS queries to malicious domains
- Unexpected port openings
SIEM Query:
source="router.log" AND ("command injection" OR "DynDNS" AND "username")🔗 References
- https://github.com/JZP018/vuln03/blob/main/linksys/E5600/CI_ddnsStatus_DynDNS_username/CI_ddnsStatus_DynDNS_username.pdf
- https://github.com/JZP018/vuln03/blob/main/linksys/E5600/CI_ddnsStatus_DynDNS_username/CI_ddnsStatus_DynDNS_username.py
- https://github.com/JZP018/vuln03/blob/main/linksys/E5600/CI_ddnsStatus_DynDNS_username/CI_ddnsStatus_DynDNS_username.pdf
