CVE-2026-76071 is a stack-based buffer overflow vulnerability in Netis NC63 firmware through version 3.0.0.3327. The vulnerability is triggered by supplying an oversized destHost parameter to the ipFilterList=mod action in the netis.cgi interface. The root cause is the use of widthless sscanf conversions that copy user-supplied input into fixed-size stack buffers without proper bounds checking and before authentication verification. Because the Boa web server executes CGI scripts with root privileges, successful exploitation allows unauthenticated remote attackers to execute arbitrary code as root on the device.

An unauthenticated remote attacker can achieve remote code execution with root privileges on affected Netis NC63 devices. This allows full control over the device, potentially leading to device compromise, network pivoting, or persistent malware installation. The vulnerability has a CVSS 4.0 base score of 9.3 (critical), reflecting its ease of exploitation and high impact.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the device's management interface from untrusted networks to reduce exposure. Monitor vendor communications for updates on patches or mitigations.