Input validation vulnerability in Link Shield 0.5.4

The Link Shield plugin for WordPress has a security issue that affects all versions up to 0.5.4. This is because it does not properly check for a special code called a “nonce” in the link_shield_menu_options() function. This allows attackers who are not logged in to the website to change settings and insert harmful code through a fake request, if they can convince the site administrator to do something like click on a link.