On Monday Internet security researches discovered a critical vulnerability in a piece of of software called OpenSSL. The so-called Heartbleed vulnerability affected numerous sites on the Internet that rely on OpenSSL to provide encrypted connections over HTTPS. This bug has been present in the library since March of 2012 and allows malicious users to gain direct access to the memory of a server terminating an HTTPS connection.
We want to let our users know that we were among almost 66% of sites on the Internet vulnerable to this bug, and your data (including your Zooniverse password) might have been compromised due to this exploit. As of now, all our infrastructure has been updated to secure against the Heartbleed vulnerability, and our SSL certificates have been changed.
Unfortunately given the nature of the vulnerability we cannot know what, if anything, may have been obtained, but as a precaution we are recommending that our users change their passwords on the Zooniverse just in case.
Zooniverse 
Professional response.
The given link is https://www.zooniverse.org/password/reset, but there is another way, which I used to change my password.: I changed it in the Account settings.: https://www.zooniverse.org/account/password
PS: I suggest, that you inform the users by e-mail, that you recommend, that they should change their passwords.