Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Johan van der Wijk Content Blocks (Custom Post Widget) allows Stored XSS.This issue affects Content Blocks (Custom Post Widget): from n/a through 3.3.0.

The Content Blocks (Custom Post Widget) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's contentblock shortcode in all versions up to, and including, 3.3.9 due to insufficient input sanitization and output escaping on user supplied values consumed from user-created content blocks. 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.

The Content Blocks (Custom Post Widget) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'contentblock' 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.

The Content Blocks (Custom Post Widget) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘content’ parameter within the plugin's shortcode Content Block in all versions up to, and including, 3.3.5 due to insufficient input sanitization and output escaping. 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.