CM CSS Columns WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the CM CSS Columns plugin for WordPress, affecting all versions through 1.2.1. The issue arises from inadequate input sanitization and output escaping of user-supplied attributes, particularly the 'tag' shortcode attribute. This vulnerability allows authenticated attackers with Contributor-level access and above to inject arbitrary web scripts into pages, which are executed when users access the affected page.

Impact

Exploitation of this vulnerability allows for stored cross-site scripting, where injected scripts are executed in the context of the user viewing the page.

Reproduction

To reproduce this vulnerability, an authenticated user with Contributor-level access or higher can use the 'tag' shortcode attribute to inject a script. The lack of proper sanitization and escaping allows the script to be executed when the page is viewed.