If you've been having a problem logging on to a server for a nice session of Minecraft, don't worry too much, the problem's not on your end.
Ever heard of Heartbleed? While it's ominous sounding, it's not a major medical issue, though it can ruin your whole day if you're not careful.
As ArsTechnica describes it, it's not so much a bug, but rather, "an extremely critical defect in the cryptographic software library an estimated two-thirds of Web servers use to identify themselves to end users and prevent the eavesdropping of passwords, banking credentials, and other sensitive data." More information on it can be found here.
While Mojang's servers for Minecraft weren't open to the exploit, load balancers the company used from Amazon were, according to a tweet from the company's coder, Kristogger Jelbring. Shutting down the servers until things could be adjusted was a precautionary measure.
Servers have since been taken back online, and most problems seems to have been resolved. Still, the company is advising that players should consider changing their password, as the potential exists that personal information could have been accessed. Unfortunately, there's no way to be sure.
A statement from Mojang reads, "Due to an exploit in the OpenSSL software used by Amazon's load balancing service (which we use for most of our stuff) we were forced to temporary suspend all of our services. All systems are now back online, and the exploit has been fixed. There was no way to target specific users, but we can not guarantee that your information wasn't compromised. Therefore we recommend everyone to change their Mojang/Minecraft account passwords."
