AT&T SMS vulnerability leading to Twitter account thefts?

I know very little information at this time but apparently some sort of vulnerability in AT&T's SMS tools has lead to an issue where malicious parties can gain access to incoming SMS messages.

This in turn allows them to use SMS based account recovery procedures to gain illicit access to additional account.

Most prominently this has lead to the compromise of https://twitter.com/uberfacts

I'm seeking additional information on the exploit but have found none so far.