Patch source: http://sophie.zarb.org/rpms/68e90a72e0052022f558148d97c9ea2a/files/1

--- a/libgtklp/libgtklp.c	2020-08-25 17:31:52.427298559 +0100
+++ b/libgtklp/libgtklp.c	2020-08-25 17:36:37.728154682 +0100
@@ -939,7 +939,7 @@
 		gtk_widget_show(pixmapwid);
 
 		if (strlen(gerror2) == 0)
-			snprintf(tmplabel, (size_t) MAXLINE, gerror1);
+			snprintf(tmplabel, (size_t) MAXLINE, "%s", gerror1);
 		else
 			snprintf(tmplabel, (size_t) MAXLINE, gerror1, gerror2);
 		label = gtk_label_new(tmplabel);
@@ -973,7 +973,7 @@
 #endif
 	} else {
 		if (strlen(gerror2) == 0)
-			g_warning(gerror1);
+			g_warning("%s", gerror1);
 		else
 			g_warning(gerror1, gerror2);
 	}