An issue in DrayTek Vigor310 devices through 4.3.2.6 allows an attacker to obtain sensitive information because the httpd server of the Vigor management UI uses a static string for seeding the PRNG of OpenSSL.

DrayTek Vigor310 devices through 4.3.2.6 allow a remote attacker to execute arbitrary code via the function ft_payload_dns(), because a byte sign-extension operation occurs for the length argument of a _memcpy call, leading to a heap-based Buffer Overflow.

DrayTek Vigor3910 devices through 4.3.2.6 allow unauthenticated DOM-based reflected XSS.

Stored XSS, by authenticated users, is caused by poor sanitization of the Login Page Greeting message in DrayTek Vigor310 devices through 4.3.2.6.

Draytek Vigor Routers firmware versions below 3.9.6/4.2.4, Access Points firmware versions below v1.4.0, Switches firmware versions below 2.6.7, and Myvigor firmware versions below 2.3.2 were discovered to use hardcoded encryption keys which allows attackers to bind any affected device to their own account. Attackers are then able to create WCF and DrayDDNS licenses and synchronize them from the website.

Certain Draytek products are vulnerable to Cross Site Scripting (XSS) via the wlogin.cgi script and user_login.cgi script of the router's web application management portal. This affects Vigor3910, Vigor1000B, Vigor2962 v4.3.2.1; Vigor2865 and Vigor2866 v4.4.1.0; Vigor2927 v4.4.2.2; and Vigor2915, Vigor2765, Vigor2766, Vigor2135 v4.4.2.0; Vigor2763 v4.4.2.1; Vigor2862 and Vigor2926 v3.9.9.0; Vigor2925 v3.9.3; Vigor2952 and Vigor3220 v3.9.7.3; Vigor2133 and Vigor2762 v3.9.6.4; and Vigor2832 v3.9.6.2.

An issue was discovered on certain DrayTek Vigor routers before July 2022 such as the Vigor3910 before 4.3.1.1. /cgi-bin/wlogin.cgi has a buffer overflow via the username or password to the aa or ab field.