Suddenly, after few hours, I got a mail from an Egyptian Hacker with nickname 'Dr.FarFar', claimed that he has hacked the Mark Zuckerberg's Facebook Profile and removed the Cover Photo using a private exploit.
The hacker has not provided any technical details about the vulnerability he used, but it seems that Zuckerberg has not noticed the removed Cover Photo on his profile.
It could be possible that Zuckerberg removed his Cover Photo himself, and someone is trying to take responsibility for the changes, but I still have a positive feeling that - May be a Minor, but its a Hack!
Well, we are trying to get more information from the hacker about the flaw, as well as contacted Facebook for confirmation of the hack. I will update the story shortly after getting more updates.
Update: Hacker explained, he used the Report abuse option on Zuckerberg's Cover image, and choose, 'I don't like this photo of me' and then "I used Fiddler2 Debugger Program to edit the request" he said.
Update: In a mail to THN, Facebook's spokesperson said, "There is no merit to this claim. We have confirmed there was no suspicious activity on the account."