CVE-2025-53715
📋 TL;DR
A buffer overflow vulnerability in TP-Link TL-WR841N V11 routers allows remote attackers to crash the web service, causing denial-of-service. The vulnerability exists in the Wan6to4TunnelCfgRpm.htm endpoint due to missing input validation. Only users with unsupported, end-of-life devices are affected.
💻 Affected Systems
- TP-Link TL-WR841N
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete web service crash leading to extended DoS, potentially requiring physical device reset or replacement.
Likely Case
Temporary web interface unavailability until device reboot, disrupting remote management capabilities.
If Mitigated
Minimal impact if device is behind firewall with restricted web interface access.
🎯 Exploit Status
Remote exploitation requires no authentication. Attack complexity is low due to missing input validation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: https://www.tp-link.com/us/support/faq/4569/
Restart Required: No
Instructions:
No official patch available. Device is end-of-life and no longer supported by vendor.
🔧 Temporary Workarounds
Disable web interface remote access
allPrevent external access to the vulnerable web interface
Access router admin panel > Security > Remote Management > Disable
Block access to vulnerable endpoint
linuxUse firewall rules to block access to /userRpm/Wan6to4TunnelCfgRpm.htm
iptables -A INPUT -p tcp --dport 80 -m string --string "/userRpm/Wan6to4TunnelCfgRpm.htm" --algo bm -j DROP
🧯 If You Can't Patch
- Replace affected devices with supported hardware
- Isolate vulnerable devices in separate network segment with strict access controls
🔍 How to Verify
Check if Vulnerable:
Check device hardware version on label or admin interface. If TL-WR841N V11, device is vulnerable.Check Version:
Check router web interface or physical device label for hardware versionVerify Fix Applied:
No fix available to verify. Workarounds can be tested by attempting to access blocked endpoints.📡 Detection & Monitoring
Log Indicators:
- Web service crash logs
- Repeated access attempts to /userRpm/Wan6to4TunnelCfgRpm.htm
Network Indicators:
- HTTP requests to vulnerable endpoint with malformed parameters
- Sudden loss of web interface connectivity
SIEM Query:
source="router_logs" AND (url="/userRpm/Wan6to4TunnelCfgRpm.htm" OR message="web service crash")