CVE-2025-11676
📋 TL;DR
An improper input validation vulnerability in TP-Link TL-WR940N V6 routers' UPnP modules allows unauthenticated attackers on the same network to perform denial-of-service attacks. This affects TL-WR940N V6 routers with firmware Build 220801 or earlier. Attackers must be adjacent to the target network.
💻 Affected Systems
- TP-Link TL-WR940N V6
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Router becomes completely unresponsive, requiring physical reset and disrupting all network connectivity for connected devices.
Likely Case
Temporary service disruption requiring router reboot, affecting internet connectivity for all connected devices.
If Mitigated
Limited impact with proper network segmentation and UPnP disabled.
🎯 Exploit Status
Exploitation requires network adjacency but no authentication. UPnP protocol is widely understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check TP-Link support site for latest firmware
Vendor Advisory: https://www.tp-link.com/en/support/faq/4755/
Restart Required: Yes
Instructions:
1. Visit TP-Link support site for TL-WR940N V6. 2. Download latest firmware. 3. Log into router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install new firmware. 6. Router will reboot automatically.
🔧 Temporary Workarounds
Disable UPnP
allTurn off Universal Plug and Play service to prevent exploitation
Network Segmentation
allIsolate untrusted devices from router management network
🧯 If You Can't Patch
- Disable UPnP in router settings immediately
- Implement network segmentation to limit access to router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Tools > Firmware UpgradeCheck Version:
No CLI command - check via web interface at 192.168.0.1 or 192.168.1.1Verify Fix Applied:
Verify firmware version is newer than Build 220801 and UPnP is disabled if not needed📡 Detection & Monitoring
Log Indicators:
- Multiple UPnP protocol violations
- Router reboot events
- Unusual UPnP discovery requests
Network Indicators:
- Excessive UPnP traffic to router IP
- Malformed UPnP packets
SIEM Query:
source="router_logs" AND ("UPnP" OR "SSDP") AND ("malformed" OR "invalid" OR "reboot")