Tumblr just rolled out a new update for iOS users, but this time there aren't any cool new features coming along with it. Instead, this 'very important' update is coming with a security fix and the warning that users should change their passwords immediately.
The update seems to only be for iOS users, and Tumblr Android users aren't affected by the security issue. In a blog post that Tumblr sent out, they urged iOS users to "please download this update now" and to change their passwords on other sites that use the same password. Sounds like whatever the security flaw was, it was a pretty big one. As they haven't elaborated on what it could have been, we can only speculate.
So, if you have a Tumblr app on your iPhone but don't use it much, you should change your password if it's a password you use on other sites. With social media, you can never be too safe.