This vulnerability stems from the plugin's failure to properly sanitize and escape user-provided input in the 'xlwcty_current_date' shortcode. As a result, an authenticated attacker with at least contributor-level access can inject malicious web scripts into webpages. When other users, including admins, visit these compromised pages, the injected scripts execute within their browser's context. This can lead to a range of security issues, including the theft of session tokens, credentials, and other sensitive information. The issue particularly poses a risk in environments where untrusted contributors have posting privileges. Ensuring that input handling mechanisms are robust and secure is essential in avoiding such vulnerabilities.

Limit the access of untrusted users, particularly those with contributor-level roles, as a temporary measure. Carefully review any plugins with similar functionalities to identify similar issues. Regularly update all plugins and ensure that all inputs, especially those involving user-generated content and shortcodes, are properly sanitized and escaped.