An authorized SSH client with restricted access can potentially bypass the restrictions.
CVE-2016-3115: openssh: bypass SSH restrictions
It was discovered that the OpenSSH server did not sanitize data received in requests to enable X11 forwarding. An authenticated client with restricted SSH access could possibly use this flaw to bypass intended restrictions.
Unitrends Risk Assessment: None
The Unitrends system only has one authenticated SSH user, root. So there are no restricted users with SSH access to exploit this issue.
No action is required.
For CentOS6, this could also be resolved in an updated openssh-5.3p1-114.el6 rpm from Red Hat.