The bug is caused by a flaw in OpenSSL software, which is commonly used on the Internet to provide security and privacy.
BlackBerry Messenger, or BBM, was created originally for the company's own products, but BlackBerry released software last fall which made the app available to users on iPhone and Android products. The versions that run on non-BlackBerry smartphones don't have the same security standards as a phone connected to its enterprise servers, which are the backbone of the company's security features.
A statement from the Waterloo, Ont.,-based company says investigations have found no problems from Heartbleed on Blackberry smartphones and servers, which are "fully protected from the OpenSSL issue."
But it warned that hacker attacks were possible on these other versions of BBM although they would be "extremely difficult to execute," requiring a so-called "man in the middle" attack.
Technology analyst Carmi Levy says a "man in the middle" attack intercepts data from a device before it reaches its destination server, or involves "picking off traffic as it moves in between different devices and networks."
"An attack would grab the traffic and literally steal my username and password from that exchange," he said in an interview.
"It's literally standing between you and the system you want to access and stealing the credentials as you enter them."
A spokeswoman for BlackBerry was unable to confirm whether BlackBerry would issue a software update to fix the security issues with BBM on iPhone and Android devices.
The vulnerability posed by Heartbleed came to public attention this month but researchers say it may have existed for years. Security experts say Heartbleed may undermine security features of websites and networking equipment, but the extent of the damage isn't known.
Canada Revenue Agency says it estimates the social insurance numbers of roughly 900 people were stolen from its systems through a six-hour breach before the CRA blocked public access to its online services last week.