NETGEAR WAC104 devices before 1.0.4.15 are affected by an authentication bypass vulnerability in /usr/sbin/mini_httpd, allowing an unauthenticated attacker to invoke any action by adding the &currentsetting.htm substring to the HTTP query, a related issue to CVE-2020-27866. This directly allows the attacker to change the web UI password, and eventually to enable debug mode (telnetd) and gain a shell on the device as the admin limited-user account (however, escalation to root is simple because of weak permissions on the /etc/ directory).

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of NETGEAR R6020, R6080, R6120, R6220, R6260, R6700v2, R6800, R6900v2, R7450, JNR3210, WNR2020, Nighthawk AC2100, and Nighthawk AC2400 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the mini_httpd service, which listens on TCP port 80 by default. The issue results from incorrect string matching logic when accessing protected pages. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of root. Was ZDI-CAN-11355.