Content Blocks (Custom Post Widget) < 3.3.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via content_block Shortcode

Description

The Content Blocks (Custom Post Widget) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'content_block' shortcode in all versions up to, and including, 3.3.0 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.