The Social Media Share Buttons & Social Sharing Icons WordPress plugin before 3.0.1 does not escape the post title before outputting it in an inline JavaScript event handler, allowing users with the Contributor role and above to perform Stored Cross-Site Scripting attacks which are triggered when a visitor interacts with the affected button.
Exploitation requires the Social Media Share Buttons & Social Sharing Icons WordPress plugin before 3.0.1 to be running a non-default icon display configuration.