CVE-2026-82616: Stack-based Buffer Overflow in TOTOLINK NR1800X

The vulnerability CVE-2026-82616 affects TOTOLINK NR1800X firmware version 9.1.0u.6681_B20230703. It is a stack-based buffer overflow triggered by improper handling of the FileName parameter in the setUploadSetting function of the /cgi-bin/cstecgi.cgi endpoint. The flaw allows remote attackers to execute code or cause denial of service. The CVSS 4.0 score is 9.4 (critical), reflecting network attack vector, low complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, availability, and security requirements. Public exploit code exists, but no official patch or remediation guidance has been published yet.

Successful exploitation can lead to remote code execution or denial of service on affected TOTOLINK NR1800X devices running firmware 9.1.0u.6681_B20230703. The vulnerability compromises confidentiality, integrity, and availability of the device. Given the critical CVSS score and public exploit availability, affected devices are at high risk if exposed to untrusted networks.

No official patch or remediation guidance is currently available from the vendor. Users should monitor the vendor's advisory channels for updates. Until a fix is released, restricting network access to the device's management interface and disabling remote administration features can reduce exposure. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.