A NULL pointer dereference in Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 allows attackers to cause a Denial of Service (DoS) via a crafted DHCP request.

Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 were discovered to utilize insecure versions of the functions strcmp and memcmp, allowing attackers to possibly obtain sensitive information via timing attacks.

Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 were discovered to store passwords in plaintext.

An issue in the CGI endpoint used to upload configurations in Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 allows attackers to upload a crafted kernel module, allowing for arbitrary code execution.

Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 were discovered to not utilize certificate verification, allowing attackers to upload crafted APPE modules from non-official servers, leading to arbitrary code execution.

An issue in Draytek devices Vigor 165/166 prior to v4.2.6 , Vigor 2620/LTE200 prior to v3.9.8.8, Vigor 2860/2925 prior to v3.9.7, Vigor 2862/2926 prior to v3.9.9.4, Vigor 2133/2762/2832 prior to v3.9.8, Vigor 2135/2765/2766 prior to v4.4.5.1, Vigor 2865/2866/2927 prior to v4.4.5.3, Vigor 2962/3910 prior to v4.3.2.7, Vigor 3912 prior to v4.3.5.2, and Vigor 2925 up to v3.9.6 allows attackers to upload crafted APP Enforcement modules, leading to arbitrary code execution.

DrayTek Vigor3910 devices through 4.3.2.6 have a stack-based overflow when processing query string parameters because GetCGI mishandles extraneous ampersand characters and long key-value pairs.

Several CGI endpoints are vulnerable to buffer overflows, by authenticated users, because of missing bounds checking on parameters passed through POST requests to the strcpy function on DrayTek Vigor310 devices through 4.3.2.6.

Buffer Overflow vulnerabilities exist in DrayTek Vigor310 devices through 4.3.2.6 (in the Vigor management UI) because of improper retrieval and handling of the CGI form parameters.

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

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

The CGI endpoints v2x00.cgi and cgiwcg.cgi of DrayTek Vigor3910 devices through 4.3.2.6 are vulnerable to buffer overflows, by authenticated users, because of missing bounds checking on parameters passed through POST requests to the strncpy function.

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.

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.

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.