CVE-2026-15701 describes a stack-based buffer overflow vulnerability in the Totolink NR1800X router firmware version 9.1.0u.6279_B20210910. The vulnerability resides in the Form_Logout function of the /formLogout.htm file, part of the lighttpd web server component. An attacker can remotely manipulate the Host argument to cause a stack-based buffer overflow, potentially leading to code execution or denial of service. The vulnerability has a CVSS 4.0 base score of 9.3 (critical), indicating network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. There is no vendor advisory or patch available at this time, and the exploit code has been publicly released.

Successful exploitation of this vulnerability allows a remote attacker to cause a stack-based buffer overflow in the affected router firmware, potentially leading to arbitrary code execution or denial of service. The vulnerability affects confidentiality, integrity, and availability of the device. Because the attack requires no authentication and no user interaction, the risk of exploitation is high. However, no known exploits in the wild have been reported yet.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should consider limiting network exposure of the affected device, such as restricting remote access to the management interface. Monitor vendor communications for updates and apply patches promptly once available.