Help with WordPress login flaw

I have received a few emails from readers of my site (gislounge.com) that, while surfing my web site, have found themselves logged in as myself, giving them full admin rights to my web site. This flaw seems to have occurred since upgrading to the latest version of WordPress 3.7.1. I have emailed information about the situation to security at wordpress.org.

While I am waiting to hear back, does anybody know about this flaw? I really need some suggestion on how to prevent this from happening before someone with less than honorable intentions finds themselves with access to my dashboard.

Thanks,
Caitlin