Among the 8,600-odd Tumblr accounts hacked today (Dec. 3) were the notable media brands USA Today, Reuters, CNET and The Verge, per a CNET post. An anti-blogging group—which goes by an acronym for a racist/offensive name, so click with caution—called GNAA has taken credit for the malicious effort, according to a Gawker story this afternoon.
The group overtook Tumblr accounts with a 184-word diatribe that ended by threatening affected consumers and companies that deleting the post would delete their account on the site. Such posts were tagged with the keyword "bronies," which is a group of adult fans of the animated TV show for children, My Little Pony: Friendship Is Magic.
Tumblr appears to have fixed the security hole, and the site seemingly has returned to normal.
The GNAA has targeted major Tumblr accounts before, such as those for President Obama's re-election campaign, Wikipedia and CNN.