Cross-site request forgery (CSRF) vulnerability in redpass.cgi in D-Link DSL-2640B Firmware EU4.00 allows remote attackers to hijack the authentication of administrators for requests that change the administrator password via the sysPassword parameter.

An issue was discovered on D-Link DSL-2640B B2 EU4.01B devices. The device can be reset to its default configuration by accessing an unauthenticated URL.

An issue was discovered on D-Link DSL-2640B B2 EU4.01B devices. Authentication can be bypassed when accessing cgi modules. This allows one to perform administrative tasks (e.g., modify the admin password) with no authentication.

An issue was discovered on D-Link DSL-2640B B2 EU4.01B devices. The function docgi(), which processes cgi requests supplied to the device's web servers, is vulnerable to a remotely exploitable stack-based buffer overflow. Unauthenticated exploitation is possible by combining this vulnerability with CVE-2020-9277.

An issue was discovered on D-Link DSL-2640B B2 EU4.01B devices. A hard-coded account allows management-interface login with high privileges. The logged-in user can perform critical tasks and take full control of the device.

An issue was discovered on D-Link DSL-2640B B2 EU4.01B devices. A cfm UDP service listening on port 65002 allows remote, unauthenticated exfiltration of administrative credentials.