... discovered 3 fresh and previously unknown vulnerabilities
(CVE-2016-7479, CVE-2016-7480, CVE-2016-7478) in the PHP 7
unserialize mechanism.
The first two vulnerabilities allow attackers to take full control
over servers, allowing them to do anything they want with the
website, from spreading malware to defacing it or stealing customer
data.
The last vulnerability generates a Denial of Service attack which
basically hangs the website, exhausts its memory consumption, and
shuts it down.
The PHP security team issued fixes for two of the vulnerabilities
on the 13th of October and 1st of December.