CVE-2025-11339
📋 TL;DR
A buffer overflow vulnerability in D-Link DI-7100G C1 routers allows remote attackers to execute arbitrary code by manipulating the popupId parameter in the webchat component. This affects all versions up to September 28, 2025. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- D-Link DI-7100G C1
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement into internal networks, and persistent backdoor installation.
Likely Case
Remote code execution allowing attackers to modify device configuration, intercept traffic, or use the device as a foothold for further attacks.
If Mitigated
Denial of service or temporary disruption if exploit attempts are blocked by network controls.
🎯 Exploit Status
Public exploit details are available, making weaponization likely. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.dlink.com/
Restart Required: Yes
Instructions:
1. Check D-Link website for firmware updates. 2. Download latest firmware for DI-7100G C1. 3. Upload via web interface. 4. Reboot device.
🔧 Temporary Workarounds
Block webchat access
linuxRestrict access to the vulnerable /webchat/hi_block.asp endpoint using firewall rules.
iptables -A INPUT -p tcp --dport 80 -m string --string "/webchat/hi_block.asp" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/webchat/hi_block.asp" --algo bm -j DROP
Disable web management
allTurn off web-based management interface if not required.
🧯 If You Can't Patch
- Isolate affected devices in separate network segments with strict firewall rules.
- Implement network intrusion detection to monitor for exploit attempts.
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface or via CLI. If version date is 20250928 or earlier, device is vulnerable.Check Version:
curl -s http://router-ip/ | grep -i firmwareVerify Fix Applied:
Verify firmware version is newer than 20250928 and test that /webchat/hi_block.asp endpoint no longer accepts malformed popupId parameters.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /webchat/hi_block.asp with unusually long popupId parameters
- Jhttpd process crashes or abnormal restarts
Network Indicators:
- HTTP POST requests to /webchat/hi_block.asp with buffer overflow patterns in payload
SIEM Query:
source="router_logs" AND url="/webchat/hi_block.asp" AND (payload_size>1000 OR contains(payload, "popupId="))