GPXpress WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the GPXpress plugin for WordPress, affecting all versions up to and including 1.3. The issue arises from inadequate input sanitization and output escaping of user-supplied attributes in the plugin's 'gpxpress' shortcode. 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 pages.

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 'gpxpress' shortcode and include a script in one of the attributes. Once the shortcode is saved, the injected script will execute when the page is viewed.