The SProcXFixesSelectSelectionInput function in the XFixes extension in X.Org X Window System (aka X11 or X) X11R6.8.0 and X.Org Server (aka xserver and xorg-server) before 1.16.3 allows remote authenticated users to cause a denial of service (out-of-bounds read or write) or possibly execute arbitrary code via a crafted length value. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8102