Just some hours ago, a Libyan hacker named "(The GreaT TeAm)" hacked and defaced the mailing list domain (http://lists.kali.org/cgi-bin/mailman/listinfo/kali) of Kali Linux. On the deface page hackers haven't written any message, just with greeting text "h4x3d by The GreaT TeAm" and "Libyan H4x0rz :D".
At the time of writing the homepage of the mailing list domain was showing the two lists-
The GreaT TeAm was the same hacker group who have also hacked the Egyptian Ministry of Information Website two days before, and they also defaced a NATO subdomain.
After Contacting the hacker's team, they reported that the "kali team didn't check the security for mailmanlist.net before they linked their domain "mailmanlist". The mailing list domain of Kali Linux is hosted on the Mailmanlist, and the Mailmanlist website is Vulnerable to Heartbleed vulnerability.
After exploiting the Heartbleed vulnerability, hackers have managed to gain access to the mailman list users' accounts via stolen cookies and then searched for more vulnerable web applications. This allows him to gain the administrative credentials of the Kali Linux Mailing list account.