The company clarified that it is working hard to resolve this issue and also apologized immediately.

Snapchat was first alerted to the vulnerability in August by a security group called Gibson Security. Snapchat said it made changes to its system to address the weaknesses, but the company also published a blog post downplaying the threat as "theoretical" on December 27.

Snapchat's immense popularity among young users has made it one of the most closely watched social media companies in the world, and Facebook Inc reportedly offered USD 3 billion last year in a failed acquisition bid.

Snapchat asks new users for their phone number so that their friends can find them on the service. The phone numbers were not attached to any real names. With Snapchat, users can send photos and videos that disappear shortly after they are viewed.

Launched in 2011, the app's user base continued to grow rapidly in 2013 with over 13 million people using the app in October, according to the latest available estimates from global information and measurement company Nielsen. In December alone, over 400 million pieces of content were shared through the app, according to Snapchat, based in Venice.