Snapchat is a photo-sharing social media application in which messages between users disappear 10 seconds after being viewed.
Gibson Security said it contacted the company in August after it discovered a security breach allowed access to users' full telephone numbers and user names. After failing to get a response from Snapchat officials about the breach, the security company publicly announced how it accessed the information Dec. 25.
Hackers for website SnapchatDB then used Gibson Security's information to publish the list of 4.6 million user names along with all but the last two digits of the corresponding telephone numbers, ABC News reported Wednesday. SnapchatDB said interested parties could contact them for the uncensored database including full phone numbers.
Kevin Poulsen, of Wired Magazine, said the biggest danger of the security breach is potential stalking.
"Snapchat has a very young user base. I think the greatest risk from this is that the full list with the full phone numbers winds up being posted somewhere, and then we see users being stalked," he said.
Snapchat issued a statement Dec. 27 saying it "recently added additional countermeasures" and "would continue to make improvements to combat spam and abuse."
Snapchat users can check website www.lookup.gibsonsec.org to discover if their information was leaked, ABC News said.