Several security issues were fixed in PHP.
It was discovered that PHP incorrectly handled restarting certain child processes when php-fpm is used. A remote attacker could possibly use this issue to cause a denial of service. This issue was only addressed in Ubuntu 18.04 LTS. (CVE-2015-9253)
18 September 2018
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in PHP.
It was discovered that PHP incorrectly handled restarting certain child processes when php-fpm is used. A remote attacker could possibly use this issue to cause a denial of service. This issue was only addressed in Ubuntu 18.04 LTS. (CVE-2015-9253)
It was discovered that PHP incorrectly handled certain exif tags in JPEG images. A remote attacker could possibly use this issue to cause PHP to crash, resulting in a denial of service. (CVE-2018-14851, CVE-2018-14883)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In Ubuntu 16.04 LTS and Ubuntu 18.04 LTS, this update uses a new upstream release, which includes additional bug fixes.
In general, a standard system update will make all the necessary changes.