The hacking outfit OurMine has already been responsible for a few high-profile Twitter account takeovers, but the latest may be particularly embarrassing for the company.

Twitter CEO Jack Dorsey had his account briefly hacked early this morning, as OurMine tweeted out a link to its site and a message that it was "testing your security," along with a Vine clip that has since been deleted. (Engadget caught a look at the tweets before they were removed.)

It's unclear what allowed Dorsey's account to be hijacked, although last month, Twitter took the step of locking down some accounts on the service after several million passwords — apparently from other services — were leaked. Similar hacks now include Google CEO Sundar Pichai and Mark Zuckerberg, but Dorsey is a particularly good reminder that not even the head of Twitter is immune.