Index: /trunk/src/VBox/Devices/Graphics/DevVGA-SVGA-cmd.cpp
===================================================================
--- /trunk/src/VBox/Devices/Graphics/DevVGA-SVGA-cmd.cpp	(revision 86887)
+++ /trunk/src/VBox/Devices/Graphics/DevVGA-SVGA-cmd.cpp	(revision 86888)
@@ -2601,4 +2601,10 @@
 int vmsvgaR3Process3dCmd(PVGASTATE pThis, PVGASTATECC pThisCC, SVGAFifo3dCmdId enmCmdId, uint32_t cbCmd, void const *pvCmd)
 {
+    if (enmCmdId > SVGA_3D_CMD_MAX)
+    {
+        LogRelMax(16, ("VMSVGA: unsupported 3D command %d\n", enmCmdId));
+        ASSERT_GUEST_FAILED_RETURN(VERR_NOT_IMPLEMENTED);
+    }
+
     int rcParse = VINF_SUCCESS;
     PVMSVGAR3STATE pSvgaR3State = pThisCC->svga.pSvgaR3State;