CVE-2026-51689

Incorrect access control in the setUpgradeFW function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to trigger firmware-upgrade workflow changes via sending a crafted POST request to /cgi-bin/cstecgi.cgi.

• Published Aug 31, 2026
• CVSS 9.1 critical
• 0.6% chance of exploitation in the next 30 days (EPSS)

CVE-2026-51689 at the National Vulnerability Database