CVE-2026-76869

Netcore NR255-V router firmware version 1.5.130703 contains a stack-based buffer overflow (CWE-121) in the reboot_timer_set.cgi CGI handler, caused by improper sscanf token parsing that copies attacker-supplied tokens into a fixed-size stack buffer without adequate bounds checking. A remote attacker who can reach the device's web management interface and holds the required high (administrator-level) privileges — as reflected in the PR:H scoring metric — can submit crafted input to the endpoint to corrupt stack memory, plausibly crashing the device or achieving arbitrary code execution. Organizations running this specific firmware version on the NR255-V, particularly units with the management interface exposed to untrusted networks, are affected. The flaw carries a CVSS 4.0 base score of 8.6 (high), but there is no known public proof of concept and no evidence of exploitation in the wild; it is not on the CISA KEV list.

What to do: Contact Netcore for firmware newer than 1.5.130703, as no patched version is identified in the available data. Restrict access to the web management interface so reboot_timer_set.cgi is reachable only from trusted internal networks or a management VLAN, and enforce strong, unique administrator credentials since exploitation requires elevated privileges. Monitor device logs for unexpected reboots, crashes, or anomalous requests to reboot_timer_set.cgi as indicators of exploitation attempts.