From the IOTA website;
At 04:48 UTC on Sunday morning, an automatic bot gained access to the IOTA website database and was able to exploit a bug in the IOTA code in order to reset the password for every user on the site. This is why you might not have been able to log into the site. There is no sign in the system logs that any data was read or that personal data was compromised. Once the IT team was aware of the issue, they immediately took the database offline for analysis, restored a backup, and corrected the bug. We have now been able to re-enable access to the site.
M0BLF, 27 Sep 2015