The Events Calendar Shortcode & Block Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the Events Calendar Shortcode & Block plugin for WordPress, affecting all versions through 3.1.2. The vulnerability arises from inadequate input sanitization and output escaping on user-supplied attributes, particularly the 'message' attribute of the 'ecs-list-events' shortcode. This flaw allows authenticated attackers with contributor-level access or higher 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 'ecs-list-events' shortcode and include a script in the 'message' attribute. Once the shortcode is rendered on a page, the injected script will execute when the page is viewed.

Remediation

Users are advised to update the Events Calendar Shortcode & Block plugin to version 3.1.3 or a newer patched version.