Jack was famous for demoing on stage how ATM cash machines could be hacked at the 2010 Black Hat conference.
He was due to retake the stage at Black Hat next week to demonstrate a new hack that could deactivate heart pace makers from 30-yards away, similar to the fictional attack shown on popular TV show Homeland.
Outside of his famous hacks, Jack was known as a skilled bug hunter, with his research covering multiple fields and areas.
Jack's death was confirmed by his employer IOActive via Twitter, although no details of how he died were given.
IOActive, Inc @IOActive
Lost but never forgotten our beloved pirate, Barnaby Jack has passed. He was a master hacker and dear friend. Here's to you Barnes!
Jack's death has resulted in a sea of comments from the security community with numerous ethical hackers and researchers praising his contributions to the field.
Sophos technology director James Lyne praised Jack, saying his animated live demonstrations and energy while researching should act as an example to all security researchers. "It is a sad day to learn that Barnaby Jack has passed away," he told V3.
"Barnes had a substantial contribution to the field - not least kicking off a mass of interest and research in to the less considered devices in security like ATMs.
"His demonstrations and research inspired many (and were awesome) and I truly hope that up and coming security professionals continue his work and passion."
Other contemporaries like Apple zero-day hunter Charlie Miller and chief research officer at penetration firm Rapid7, HD Moore, expressed their admiration via Twitter.
To see Jack's famous ATM hack check out the video below.