The x11_open_helper function in channels.c in ssh in OpenSSH before 6.9, when ForwardX11Trusted mode is not used, lacks a check of the refusal deadline for X connections, which makes it easier for remote attackers to bypass intended access restrictions via a connection outside of the permitted time window.
https://security.netapp.com/advisory/ntap-20181023-0001/
https://security.gentoo.org/glsa/201512-04
https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://anongit.mindrot.org/openssh.git/commit/?h=V_6_9&id=1bf477d3cdf1a864646d59820878783d42357a1d
http://www.ubuntu.com/usn/USN-2710-2
http://www.ubuntu.com/usn/USN-2710-1
http://www.securitytracker.com/id/1032797
http://www.securityfocus.com/bid/75525
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
http://www.openssh.com/txt/release-6.9
http://rhn.redhat.com/errata/RHSA-2016-0741.html
http://openwall.com/lists/oss-security/2015/07/01/10
http://lists.opensuse.org/opensuse-security-announce/2015-09/msg00017.html