The Network Posts Extended plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘post_height’ parameter in all versions up to, and including, 7.7.1 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.
https://wordpress.org/plugins/network-posts-extended/#developers