A symfony security update has been released for Debian GNU/Linux 8 LTS to address multiple vulnerabilities which could lead to a timing attack/information leak

Package : symfony
Version : 2.3.21+dfsg-4+deb8u6
CVE ID : CVE-2019-18886 CVE-2019-18887 CVE-2019-18888

Multiple vulnerabilities have been found in the Symfony PHP framework
which could lead to a timing attack/information leak, argument injection
and code execution via unserialization.

For Debian 8 "Jessie", these problems have been fixed in version
2.3.21+dfsg-4+deb8u6.

We recommend that you upgrade your symfony packages.

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS