Input validation vulnerability in Ziteboard Online Whiteboard 2.9.9

The Ziteboard Online Whiteboard plugin for WordPress has a security vulnerability that allows attackers, who have contributor-level access or higher, to inject malicious code into pages on WordPress websites. This code will then execute on the website whenever someone visits the page with the malicious code. This vulnerability exists in versions up to and including 2.9.9 of the Ziteboard plugin, due to the plugin not properly sanitizing user input or properly escaping output.