CVE-2026-51624 Overview
CVE-2026-51624 is an access control vulnerability in the getStationMacByIp function of the TOTOLINK T6 router running firmware version 4.1.5cu.748_B20211015. Unauthenticated remote attackers can retrieve client MAC addresses by sending a crafted POST request to the /cgi-bin/cstecgi.cgi endpoint. The flaw is classified under [CWE-284: Improper Access Control]. Successful exploitation exposes network-connected client identifiers without any authentication or user interaction, enabling reconnaissance against the target wireless network.
Critical Impact
Unauthenticated network attackers can enumerate connected client MAC addresses, supporting downstream attacks such as MAC spoofing, targeted deauthentication, and device fingerprinting.
Affected Products
- TOTOLINK T6 router
- Firmware version 4.1.5cu.748_B20211015
- CGI handler /cgi-bin/cstecgi.cgi exposing the getStationMacByIp function
Discovery Timeline
- 2026-08-28 - CVE-2026-51624 published to NVD
- 2026-09-01 - Last updated in NVD database
Technical Details for CVE-2026-51624
Vulnerability Analysis
The TOTOLINK T6 router exposes a management interface through the cstecgi.cgi binary. This CGI handler dispatches JSON-formatted POST requests to internal functions based on a topicurl parameter. The getStationMacByIp function returns the MAC address associated with a supplied IP address on the local network.
The function fails to verify whether the requester holds an authenticated session. Any network-reachable client can invoke it directly, bypassing the login and session validation checks that other management endpoints enforce. Because MAC addresses uniquely identify wireless clients, disclosure of this information supports targeted deauthentication, MAC-based access control bypass, and correlation of devices to physical users.
Root Cause
The root cause is missing authorization enforcement on the getStationMacByIp handler within /cgi-bin/cstecgi.cgi. The CGI dispatcher routes the request to the function without invoking the session token or cookie validation routine used elsewhere in the firmware. Improper access control [CWE-284] permits unauthenticated invocation of a sensitive information-disclosure primitive.
Attack Vector
The attack requires only network access to the router's HTTP management interface. An attacker sends a crafted POST request to /cgi-bin/cstecgi.cgi containing a topicurl value of getStationMacByIp along with a target IP address. The router responds with the corresponding MAC address without prompting for credentials. No user interaction is required, and the exploit is repeatable to enumerate every host on the LAN.
No verified public proof-of-concept code is referenced in the enriched data. See the GitHub Vendor Coordination Overview for technical details.
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Stop Identity AttacksDetection Methods for CVE-2026-51624
Indicators of Compromise
- Unauthenticated HTTP POST requests to /cgi-bin/cstecgi.cgi containing the getStationMacByIp topic value.
- Repeated CGI requests iterating through sequential LAN IP addresses from a single external or wireless source.
- HTTP responses from the router containing MAC address strings correlated to requests without a preceding authenticated session.
Detection Strategies
- Inspect router HTTP access logs for POST traffic to cstecgi.cgi where no valid session cookie or authentication header is present.
- Deploy network intrusion detection signatures that match the getStationMacByIp string in HTTP request bodies destined for TOTOLINK management interfaces.
- Alert on rapid sequential requests to the CGI endpoint that suggest scripted enumeration behavior.
Monitoring Recommendations
- Forward router syslog and web management logs to a centralized logging platform for retention and correlation.
- Baseline normal administrative traffic to the router and flag deviations, especially requests originating from the WAN interface.
- Monitor wireless client tables for signs of MAC spoofing that could follow reconnaissance based on this disclosure.
How to Mitigate CVE-2026-51624
Immediate Actions Required
- Restrict access to the router's HTTP management interface to trusted management VLANs and disable remote (WAN-side) administration.
- Segment IoT and guest devices from administrative networks to limit exposure of the LAN-side management interface.
- Audit the TOTOLINK Firmware Download Page for firmware releases newer than 4.1.5cu.748_B20211015 and apply any security updates.
Patch Information
At the time of publication, the enriched data does not identify a specific vendor patch addressing CVE-2026-51624. Consult the TOTOLINK Official Website and the GitHub Vendor Coordination Overview for the current disclosure status and any subsequent firmware releases.
Workarounds
- Block inbound access to TCP ports serving the router web UI at the perimeter until a fixed firmware version is available.
- Place the router behind an upstream firewall that terminates management traffic and enforces authenticated access via VPN.
- Replace end-of-support hardware with devices that receive active vendor security maintenance if no patch is issued.
# Configuration example: restrict management interface exposure on an upstream firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -m iprange ! --src-range <admin_subnet> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -m iprange ! --src-range <admin_subnet> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
