Smart Post <= 4.0.9 - Authenticated (Subscriber+) Stored Cross-Site Scripting via User display_name via Author Filter block

The Smart Post – Post Grid, Post Carousel, Post Slider Gutenberg Blocks for Blog & News plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'display_name' parameter in all versions up to, and including, 4.0.9 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires the victim page to contain an Author Filter block alongside a grid or live-filter block, and execution is triggered by a visitor clicking the attacker's author entry in the dropdown — a standard filter interaction requiring no elevated privileges from the victim.