Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp	(revision 50447)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceVMInfo.cpp	(revision 50448)
@@ -797,18 +797,21 @@
 
     /* Build the user list. */
-    if (RT_SUCCESS(rc))
-        rc = RTStrAllocEx(&pszUserList, cchUserList + 1);
-    if (RT_SUCCESS(rc))
-    {
-        char *psz = pszUserList;
-        for (uint32_t i = 0; i < cUsersInList; i++)
-        {
-            if (i != 0)
-                *psz++ = ',';
-            size_t cch = strlen(papszUsers[i]);
-            memcpy(psz, papszUsers[i], cch);
-            psz += cch;
-        }
-        *psz = '\0';
+    if (cchUserList > 0)
+    {
+        if (RT_SUCCESS(rc))
+            rc = RTStrAllocEx(&pszUserList, cchUserList + 1);
+        if (RT_SUCCESS(rc))
+        {
+            char *psz = pszUserList;
+            for (uint32_t i = 0; i < cUsersInList; i++)
+            {
+                if (i != 0)
+                    *psz++ = ',';
+                size_t cch = strlen(papszUsers[i]);
+                memcpy(psz, papszUsers[i], cch);
+                psz += cch;
+            }
+            *psz = '\0';
+        }
     }