Earlier this week, Opera detected the signs of an attack where access was gained to Opera sync system.
But, the attack was quickly blocked by the Opera.
Although after having such good features it has not been able to assert itself due to strong competitors.

Opera has acknowledged the problem and is trying to solve.
It was on its official blog that the Opera has made known its latest problem.
A hacker broke into its servers successfully, and user data were stolen.

The attack must have happened earlier this week.
The stolen data is stored thanks to its synchronization service Opera Sync enabling you to store and access remotely.
you might also sync with other instances of Opera that are already running on other machines.

Although they were stolen, the passwords are encrypted or having some strong encryption.