The image, which is too graphic to publish, appears to show the Cronulla Sharks player engaged in a lewd act while standing at a urinal.
The Sharks chief executive, Steve Noyce, told Fairfax Media that he had been in contact with the NRL about the image.
"I am aware of the photo," Mr Noyce said. "I've spoken to the NRL and we'll investigate the matter."
NRL officials and the Sharks are trying to determine the authenticity of the photo and how it was shared on social media.
The image was published on Twitter and has since been retweeted and shared with comments.
Carney's agent, David Riolo, told Fairfax Media he was unable to comment while the matter was under investigation.
It is the latest incident to hurt Carney’s career, which has been marred by alcohol-related issues.
Carney joined the Sharks in 2012 after being dismissed two years into a three-year contract with the Roosters after he broke a club-issued alcohol ban in 2011.
He had previously spent a year playing for a regional Queensland team after a string of alcohol-related incidents during his time playing for the Canberra Raiders.
The 2010 Dally M medal winner also played for NSW in the State of Origin for the first time in 2012.
Carney starred in Cronulla's astonishing 24-22 come-from-behind win over the Broncos in Brisbane on Friday night.
Read more: http://www.smh.com.au/rugby-league/leag ... z35zIomNP1
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