"I came across this bug during a voice call with my friend. The bug used to allow the caller to upgrade it to a video call without the knowledge of the receiver," the 22-year-old engineer said.
"I reported the matter in March to the Bug Bounty Program of Facebook, which deals with the violation of privacy matters. The report was acknowledged by the Facebook Security team the next day and its technical department fixed the bug within 15-20 days," he added.
The social media giant named the engineer on a list where it has thanked those who make "a responsible disclosure". The list for 2019 contains 96 names so far where Zonel is at the 16th spot.
Facebook, owned by Mark Zuckerberg, had purchased WhatsApp for USD 19 billion in February 2014.
Earlier this month, there were reports that a 19-year-old from Kerala had also been awarded by Facebook for finding a bug on WhatsApp.