A libssh security update has been released for Debian GNU/Linux 8 LTS

Package : libssh
Version : 0.6.3-4+deb8u4
CVE ID : CVE-2019-14889
Debian Bug : 946548

It was found that libssh, a tiny C SSH library, does not sufficiently
sanitize path parameters provided to the server, allowing an attacker
with only SCP file access to execute arbitrary commands on the server.

For Debian 8 "Jessie", this problem has been fixed in version
0.6.3-4+deb8u4.

We recommend that you upgrade your libssh 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