The Packers have suffered something of an injury crisis at quarterback recently, with Aaron Rodgers breaking his collarbone and back-up Seneca Wallace picking up a groin problem early in the 27-13 loss to the Philadelphia Eagles on Sunday.
Scott Tolzien replaced Wallace in that match and will start next Sunday's game against the New York Giants, but McCarthy is said to be keen on bringing Flynn in as extra cover for his third-choice quarterback.
"[Flynn] went through his workout this morning. [He] looks good. That's really all I have for you right now. Everything else is a work in progress," NFL.com quotes McCarthy as saying.
"A lot of the information that you need to make decisions is still coming in, so we're still trying to put it all together."
Flynn played for the Packers between 2008 and 2012, throwing for a franchise-record 480 yards and six touchdowns in his final game for the team.