X.Org Server (aka xserver and xorg-server) 1.15.0 through 1.16.x 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 or index value to the (1) sproc_dri3_query_version, (2) sproc_dri3_open, (3) sproc_dri3_pixmap_from_buffer, (4) sproc_dri3_buffer_from_pixmap, (5) sproc_dri3_fence_from_fd, (6) sproc_dri3_fd_from_fence, (7) proc_present_query_capabilities, (8) sproc_present_query_version, (9) sproc_present_pixmap, (10) sproc_present_notify_msc, (11) sproc_present_select_input, or (12) sproc_present_query_capabilities function in the (a) DRI3 or (b) Present extension.