CVE-2026-2566
📋 TL;DR
A remote stack-based buffer overflow vulnerability exists in Wavlink WL-NU516U1 routers through firmware version 130/260. Attackers can exploit this by manipulating the firmware_url parameter in the /cgi-bin/adm.cgi endpoint to execute arbitrary code or crash the device. This affects all users of vulnerable Wavlink WL-NU516U1 routers with exposed web interfaces.
💻 Affected Systems
- Wavlink WL-NU516U1
⚠️ 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
Remote code execution leading to complete device compromise, persistence, lateral movement, and data exfiltration.
Likely Case
Device crash causing denial of service, potentially requiring physical reset.
If Mitigated
Limited impact if device is behind firewall with no internet exposure.
🎯 Exploit Status
Public exploit details available on GitHub, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch available. Vendor has not responded to disclosure.
🔧 Temporary Workarounds
Block CGI Access
linuxBlock access to the vulnerable /cgi-bin/adm.cgi endpoint using firewall rules.
iptables -A INPUT -p tcp --dport 80 -m string --string "/cgi-bin/adm.cgi" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/cgi-bin/adm.cgi" --algo bm -j DROP
Disable Web Interface
allDisable the router's web administration interface if not required.
🧯 If You Can't Patch
- Replace vulnerable devices with supported alternatives
- Isolate devices in separate network segments with strict firewall rules
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at http://[router-ip]/ or SSH if enabled. Version should be higher than 130/260.Check Version:
curl -s http://[router-ip]/ | grep -i version || ssh admin@[router-ip] "cat /etc/version"Verify Fix Applied:
No official fix available to verify. Workarounds can be tested by attempting to access /cgi-bin/adm.cgi.📡 Detection & Monitoring
Log Indicators:
- Multiple requests to /cgi-bin/adm.cgi with long firmware_url parameters
- Device crash/reboot logs
Network Indicators:
- HTTP POST requests to /cgi-bin/adm.cgi with unusually long parameters
- Traffic patterns suggesting buffer overflow attempts
SIEM Query:
source="router_logs" AND uri="/cgi-bin/adm.cgi" AND (param_length>1000 OR status=500)