Citrix Online Plug-in for Windows for XenApp & XenDesktop before 11.2, Citrix Online Plug-in for Mac for XenApp & XenDesktop before 11.0, Citrix ICA Client for Linux before 11.100, Citrix ICA Client for Solaris before 8.63, and Citrix Receiver for Windows Mobile before 11.5 allow remote attackers to execute arbitrary code via (1) a crafted HTML document, (2) a crafted .ICA file, or (3) a crafted type field in an ICA graphics packet, related to a "heap offset overflow" issue.