CVE-2025-29523
📋 TL;DR
This CVE describes a command injection vulnerability in D-Link DSL-7740C routers that allows attackers to execute arbitrary commands via the ping6 function. Attackers can potentially gain full control of affected devices. This affects D-Link DSL-7740C router users with vulnerable firmware versions.
💻 Affected Systems
- D-Link DSL-7740C
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent backdoors, intercept network traffic, pivot to internal networks, or use device as botnet node.
Likely Case
Router takeover enabling network traffic monitoring, DNS hijacking, credential theft, and lateral movement to connected devices.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
🎯 Exploit Status
Proof of concept available in GitHub gist; command injection vulnerabilities are frequently weaponized due to their simplicity and impact.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Check D-Link security bulletin for firmware updates. 2. Download latest firmware from D-Link support site. 3. Access router admin interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable WAN management
allPrevent external access to router management interface
Network segmentation
allIsolate router from critical internal networks
🧯 If You Can't Patch
- Replace affected router with supported model
- Implement strict firewall rules blocking all unnecessary inbound traffic to router
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Information or Firmware Update sectionCheck Version:
Login to router admin interface and navigate to System Status or Firmware Information pageVerify Fix Applied:
Verify firmware version has been updated to a version newer than DSL7740C.V6.TR069.20211230📡 Detection & Monitoring
Log Indicators:
- Unusual ping6 commands in router logs
- Multiple failed authentication attempts followed by ping6 requests
- Unexpected system command execution in logs
Network Indicators:
- Unusual outbound connections from router
- Suspicious traffic patterns from router to external IPs
- DNS queries to malicious domains from router
SIEM Query:
source="router_logs" AND ("ping6" OR "command injection" OR "arbitrary command")