The security blog of Opera browser has an interesting short write-up about a security breach that happened to them:
Earlier this week, we detected signs of an attack where access was gained to the Opera sync system. This attack was quickly blocked. Our investigations are ongoing, but we believe some data, including some of our sync users' passwords and account information, such as login names, may have been compromised.
[...] The total active number of users of Opera sync in the last month is 1.7 million, less than 0.5% of the total Opera user base of 350 million people.
(Score: 2) by richtopia on Monday August 29 2016, @05:49PM
You are completely correct. I wish more browsers would use the Firefox Sync architecture, even if they are using different servers. Same function and encrypted.
https://en.wikipedia.org/wiki/Firefox_Sync [wikipedia.org]