Tumblr has just released a “very important” security update for their iOS app that they say will address a significant flaw that allowed for passwords to be compromised in “certain circumstances.”

In order to make sure your account is secure, Tumblr says you should download the update and change your password. If you’ve been using the same password for Tumblr as for other logins, you should also think about changing it as well.

In a statement, Tumblr would only identify the problem as a “security vulnerability” – no more specificity than that:

Earlier today, Tumblr was notified of a security vulnerability introduced in our iOS app. We immediately released an update that repairs the issue and are notifying affected users. We obviously take these incidents very seriously and deeply regret this error.

The vulnerability does not seem to have affected Tumblr’s Android app.

“Please know that we take your security very seriously and are tremendously sorry for this lapse and inconvenience,” says Tumblr’s Joe Stanley.

Tumblr is now a Yahoo property, of course. That deal became official on June 20th.

You can grab the update now over at the App Store.