Monstra CMS v3.0.4 contains an arbitrary file upload vulnerability in the Files Manager plugin. The application relies on blacklist-based file extension validation and stores uploaded files directly in a web-accessible directory. Under typical server configurations, this can allow an attacker to upload files that are interpreted as executable code, resulting in remote code execution.

A cross-site scripting (XSS) vulnerability in Monstra CMS v3.0.4 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the About Me parameter in the Edit Profile page.

A cross-site scripting (XSS) vulnerability in Monstra CMS v3.0.4 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the Themes parameter at index.php.

Cross Site Scripting vulnerabilty in Monstra CMS 3.0.4 via the page feature in admin/index.php.

Monstra CMS 3.0.4 allows attackers to execute arbitrary code via a crafted payload entered into the "Snippet content" field under the "Edit Snippet" module.

A stored cross site scripting (XSS) vulnerability in Monstra CMS version 3.0.4 allows attackers to execute arbitrary web scripts or HTML via crafted a payload entered into the "Site Name" field under the "Site Settings" module.

An issue in Monstra CMS v3.0.4 allows attackers to execute arbitrary web scripts or HTML via bypassing the file extension filter and uploading crafted HTML files.

Monstra CMS 3.0.4 allows an attacker, who already has administrative access to modify .chunk.php files on the Edit Chunk screen, to execute arbitrary OS commands via the Theme Module by visiting the admin/index.php?id=themes&action=edit_chunk URI. NOTE: there is no indication that the Edit Chunk feature was intended to prevent an administrator from using PHP's exec feature

Monstra CMS 1.6 allows XSS via an uploaded SVG document to the admin/index.php?id=filesmanager&path=uploads/ URI. NOTE: this is a discontinued product.

plugins/box/users/users.plugin.php in Monstra CMS 3.0.4 allows Login Rate Limiting Bypass via manipulation of the login_attempts cookie.

Monstra CMS 3.0.4 and earlier has XSS via index.php.