Integer overflow in X.org libXfixes before 5.0.3 on 32-bit platforms might allow remote X servers to gain privileges via a length value of INT_MAX, which triggers the client to stop reading data and get out of sync.
https://security.gentoo.org/glsa/201704-03
https://lists.x.org/archives/xorg-announce/2016-October/002720.html
https://cgit.freedesktop.org/xorg/lib/libXfixes/commit/?id=61c1039ee23a2d1de712843bed3480654d7ef42e
http://www.securitytracker.com/id/1036945
http://www.securityfocus.com/bid/93361