Input validation vulnerability in Skype Legacy Buttons 3.1

The Skype Legacy Buttons plugin for WordPress has a security vulnerability that allows attackers with contributor-level or higher permissions to add malicious code to pages. This code can then be executed by anyone who accesses the page, and can be used to steal information or damage the page. The vulnerability is present in all versions up to 3.1, and is due to the plugin not properly checking user input and protecting it from malicious code.