Incorrect access control in the getTelnetCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain Telnet service… (CVE-2026-51664)

The vulnerability in TOTOLINK T6 4.1.5cu.748_B20211015 involves improper access control in the getTelnetCfg function. Specifically, unauthenticated attackers can send a crafted POST request to the /cgi-bin/cstecgi.cgi CGI endpoint to obtain information about whether the Telnet service is enabled on the device. This information disclosure could aid attackers in further targeting the device but does not indicate direct remote code execution or privilege escalation from the provided data.

Unauthenticated attackers can obtain Telnet service enablement status information from the affected device. This may facilitate reconnaissance and subsequent attacks if Telnet is enabled, but the vulnerability itself does not directly grant access or control over the device.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided in the available data. Until a patch is available, restricting network access to the device's management interfaces and disabling Telnet service if not needed may reduce exposure.