xfsettingsd does some string formating in registry.c without checking its string parameters for nullness. (line 306 and 358) Since the default value for one XSETTING_ENTRY_GTK_CURSORTHEMENAME property is NULL which is used as a formating parameter it causes a segfault. The attached patch adds checks for nullness and fixes the problem.
Created attachment 2077 add checks for nullness to avoid segfault
Fixed. Patch applied in revision 29277.