The 'Forever' star features on remixes of Kanye West's latest song 'Theraflu' (recently retitled 'Way Too Cold' and then simply 'Cold') and appears to insult an ex-girlfriend, who some believed to be Rihanna.
Lyrics for 'Cold' include: "Don't f**k with my old bitch it's like a bad fur/ Every industry n***a done had her/ Shook the tree like a pumpkin just to smash her/ Bitch is breaking codes, but I'm the password."
The track appeared to offend Rihanna, who unfollowed Brown on Twitter in the hours after 'Cold's release. Brown later stopped following Rihanna as well.
Brown addressed the controversy in a Twitter post on Thursday (May 10).
He wrote: "Assumptions! I didn't say any names so if u took offence to it then its something you feel guilty about."
This development comes two months after the former couple collaborated on a pair of new remixes for 'Birthday Cake' and 'Turn Up The Music'.
The stars famously dated for several years, but their relationship ended in 2009 when Brown assaulted Rihanna.
Listen to Chris Brown's freestyle over Kanye West's 'Theraflu' below: