Index: /trunk/src/VBox/Main/include/GuestDnDPrivate.h
===================================================================
--- /trunk/src/VBox/Main/include/GuestDnDPrivate.h	(revision 58231)
+++ /trunk/src/VBox/Main/include/GuestDnDPrivate.h	(revision 58232)
@@ -596,4 +596,7 @@
             return VINF_SUCCESS;
         }
+
+        if (!RTStrIsValidEncoding(pszList))
+            return VERR_INVALID_PARAMETER;
 
         RTCList<RTCString> lstURIOrg = RTCString(pszList, cbList).split("\r\n");
Index: /trunk/src/VBox/Main/src-client/GuestDnDPrivate.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/GuestDnDPrivate.cpp	(revision 58231)
+++ /trunk/src/VBox/Main/src-client/GuestDnDPrivate.cpp	(revision 58232)
@@ -388,6 +388,11 @@
             AssertReturn(DragAndDropSvc::CB_MAGIC_DND_HG_REQ_DATA == pCBData->hdr.u32Magic, VERR_INVALID_PARAMETER);
 
-            if (   pCBData->cbFormat == 0
-                || pCBData->cbFormat > _64K) /** @todo Make this configurable? */
+            if (   pCBData->cbFormat  == 0
+                || pCBData->cbFormat  > _64K /** @todo Make this configurable? */
+                || pCBData->pszFormat == NULL)
+            {
+                rc = VERR_INVALID_PARAMETER;
+            }
+            else if (!RTStrIsValidEncoding(pCBData->pszFormat))
             {
                 rc = VERR_INVALID_PARAMETER;
@@ -427,6 +432,11 @@
             AssertReturn(DragAndDropSvc::CB_MAGIC_DND_GH_ACK_PENDING == pCBData->hdr.u32Magic, VERR_INVALID_PARAMETER);
 
-            if (   pCBData->cbFormat == 0
-                || pCBData->cbFormat > _64K) /** @todo Make the maximum size configurable? */
+            if (   pCBData->cbFormat  == 0
+                || pCBData->cbFormat  > _64K /** @todo Make the maximum size configurable? */
+                || pCBData->pszFormat == NULL)
+            {
+                rc = VERR_INVALID_PARAMETER;
+            }
+            else if (!RTStrIsValidEncoding(pCBData->pszFormat))
             {
                 rc = VERR_INVALID_PARAMETER;