The authentication setup in XWayland 1.16.x and 1.17.x before 1.17.2 starts the server in non-authenticating mode, which allows local users to read from or send information to arbitrary X11 clients via vectors involving a UNIX socket.

X.Org Server (aka xserver and xorg-server) before 1.16.3 and 1.17.x before 1.17.1 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (crash) via a crafted string length value in a XkbSetGeometry request.

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.

Integer overflow in the ProcDRI2GetBuffers function in the DRI2 extension in X.Org Server (aka xserver and xorg-server) 1.7.0 through 1.16.x before 1.16.3 allows remote authenticated users to cause a denial of service (crash) or possibly execute arbitrary code via a crafted request, which triggers an out-of-bounds read or write.

Buffer overflow in the compNewPixmap function in compalloc.c in the Composite extension for the X.org X11 server before 1.4 allows local users to execute arbitrary code by copying data from a large pixel depth pixmap into a smaller pixel depth pixmap.