Thats way to vague to be threatening. You can be as paranoid if you want ("you" generally, not you specifically), but that fact that you use the internet at all means that you're at high risk. Sure, to be "safe" a website could spend 100's, if not 1000's or even 10's of 1000's of dollars on a monthly basis, but a forum with a handful of users just isn't worth that kind of trouble.
Sure heartbleed shows that someone, or a group of someones, can hack any system no matter how secure... But reCAPTCHA, and CAPTCHA, have been around for years. They still exist and serve a purpose because they protect low priority sites (typically). Small, uninteresting sites are at less risk because there is low reward for "hacking" the site.
Kind of off topic... Lets stay on topic by suggesting things better than recaptcha : )