CVE-2026-1686
π TL;DR
A remote buffer overflow vulnerability in Totolink A3600R routers allows attackers to execute arbitrary code by manipulating the apcliSsid parameter in the setAppEasyWizardConfig function. This affects version 5.9c.4959 of the firmware and can be exploited without authentication. Organizations using these routers are at risk of complete system compromise.
π» Affected Systems
- Totolink A3600R
β οΈ Risk & Real-World Impact
Worst Case
Complete system takeover with root privileges, enabling persistent backdoor installation, network pivoting, and data exfiltration.
Likely Case
Remote code execution leading to router compromise, enabling man-in-the-middle attacks, credential theft, and botnet recruitment.
If Mitigated
Limited impact if network segmentation isolates routers and strict firewall rules prevent external access to vulnerable services.
π― Exploit Status
Proof-of-concept exploit code is publicly available on GitHub, making exploitation straightforward for attackers.
π οΈ Fix & Mitigation
β Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Totolink's official website for firmware updates. 2. Download the latest firmware for A3600R. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply the new firmware. 6. Reboot the router.
π§ Temporary Workarounds
Disable Remote Management
allPrevent external access to the router's management interface
Access router admin panel β System β Remote Management β Disable
Network Segmentation
allIsolate vulnerable routers from critical network segments
Configure firewall rules to restrict access to router management ports (typically 80, 443, 8080)
π§― If You Can't Patch
- Replace vulnerable routers with supported models from different vendors
- Implement strict network access controls to limit exposure to the router's management interface
π How to Verify
Check if Vulnerable:
Check firmware version in router admin interface: System β Firmware Upgrade β Current Version should show 5.9c.4959Check Version:
curl -s http://router-ip/version or check web interfaceVerify Fix Applied:
Verify firmware version has changed from 5.9c.4959 to a newer version after patchingπ‘ Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/cstecgi.cgi with apcliSsid parameter
- Multiple failed login attempts followed by buffer overflow patterns
Network Indicators:
- Unusual outbound connections from router to unknown IPs
- Traffic spikes on router management ports
SIEM Query:
source="router_logs" AND (uri_path="/cgi-bin/cstecgi.cgi" AND apcliSsid=*) OR (event_type="buffer_overflow" AND device_model="A3600R")π References
- https://github.com/SunnyYANGyaya/cuicuishark-sheep-fishIOT/blob/main/ToTolink/A3600R/4959-apcliSsid-setAppEasyWizardConfig.md
- https://github.com/SunnyYANGyaya/cuicuishark-sheep-fishIOT/blob/main/ToTolink/A3600R/4959-apcliSsid-setAppEasyWizardConfig.md#poc
- https://vuldb.com/?ctiid.343480
- https://vuldb.com/?id.343480
- https://vuldb.com/?submit.740888
- https://www.totolink.net/
