According to Disqus, it learned of the leak Thursday evening after Troy Hunt of Have I Been Pwned notified obtained a copy of the site’s information and informed the company. Within about 24 hours, it has disclosed the breach, started to contact users and forced password resets for affected accounts.
Within the last day, Hunt has also added databases for breaches from Bit.ly and Kickstarter to his site, and he says he has three more to go. HIBP is a free service that collects the databases of account information stolen by hackers and will let you know if your information is among those affected — signing up is probably a good idea.
If you have an account with one of the services that have been pwned, then besides needing to reset your password there, you could have a problem if a password is shared across accounts on other websites. If you’ve reused a password elsewhere, then it’s time to change it everywhere, which is why a password manager (like LastPass or 1Password) to create and manage unique keys is a good idea, as well as enabling two-factor authentication wherever you can.