The remote Debian host is missing a security-related update.
Several vulnerabilities were found in PHP, a general-purpose scripting language commonly used for web application development. The vulnerabilities are addressed by upgrading PHP to the new upstream version 5.6.22, which includes additional bug fixes. Please refer to the upstream changelog for more information : - https://php.net/ChangeLog-5.php#5.6.21 - https://php.net/ChangeLog-5.php#5.6.22
Upgrade the php5 packages. For the stable distribution (jessie), these problems have been fixed in version 5.6.22+dfsg-0+deb8u1.