Not sure what issue you're referring to, but you can reach us through the contact form linked at the bottom of every page on our Q&A sites (like the one you found) or by email to team@. Mentioning something like "security vulnerability" in the subject or the body will help get it looked at faster.
Edit: checked internally, and this specific issue is being fixed as we speak.
Edit: checked internally, and this specific issue is being fixed as we speak.