diff -up xorg-server-1.1.1/Xext/cup.c.jx xorg-server-1.1.1/Xext/cup.c
--- xorg-server-1.1.1/Xext/cup.c.jx	2006-07-05 14:31:36.000000000 -0400
+++ xorg-server-1.1.1/Xext/cup.c	2007-12-11 14:28:37.000000000 -0500
@@ -198,6 +198,9 @@ int ProcGetReservedColormapEntries(
 
     REQUEST_SIZE_MATCH (xXcupGetReservedColormapEntriesReq);
 
+    if (stuff->screen >= screenInfo.numScreens)
+	return BadValue;
+
 #ifndef HAVE_SPECIAL_DESKTOP_COLORS
     citems[CUP_BLACK_PIXEL].pixel = 
 	screenInfo.screens[stuff->screen]->blackPixel;