Dropbox has been breached.

[Retarded Joker]

Dropbox has been attacked and over 60 million user details have been leaked.
If you're a Dropbox user, change your password as soon as possible and any other corresponding account with the same password.

Source: hxxp://motherboard.vice.com/read/hackers-stole-over-60-million-dropbox-accounts

Check if you've been a target: hxxps://haveibeenpwned.com/

[A440]

Umm, I just changed my pw since I appear to be on that list.

Thanks for the heads-up.

[Javelina]

It is a strange situation, in terms of chronology. You're right, that Dropbox had a data breach that exposed the stored credentials of millions of their customers. However, that breach occurred in 2012! Then in August 2016, Dropbox forced password resets for customers they believed may be at risk, according to the Motherboard article.

So, what happened that caused Dropbox to suddenly tell users to change their account passwords now, for something that happened in 2012? I'm not sure, even after I read this new Dropbox help post hxxps://www.dropbox.com/help/9257

We recently learned about an old set of Dropbox user credentials (email addresses plus hashed and salted passwords) that we believe were obtained in 2012. We first heard rumors about this set two weeks ago, and immediately began our investigation. We then emailed all users we believed were affected and completed a password reset for anyone who hadn’t updated their password since mid-2012.