Input validation vulnerability in Reusable Text Blocks 1.5.3

The Reusable Text Blocks plugin for WordPress was recently discovered to have a vulnerability that could allow attackers with certain permissions to inject malicious web scripts into pages. This vulnerability affects all versions up to and including 1.5.3, and happens because the plugin fails to properly sanitize and escape any user-supplied input. This means that if a malicious attacker could gain access to the plugin, they could inject web scripts into pages that would be executed whenever a user visited the page.