From https://lists.debian.org/debian-qa-packages/2014/12/msg00048.html , which
seems to come from Ubuntu.

Subject: Fix format string vulnerability (CVE-2014-9157) in yyerror() routine
Origin: https://github.com/ellson/graphviz/commit/99eda421f7ddc27b14e4ac1d2126e5fe41719081
Author: Emden R. Gansner

---
 lib/cgraph/scan.l |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/lib/cgraph/scan.l
===================================================================
--- a/lib/cgraph/scan.l
+++ b/lib/cgraph/scan.l
@@ -225,7 +225,7 @@
 	agxbput (&xb, buf);
 	agxbput (&xb, yytext);
 	agxbput (&xb,"'\n");
-	agerr(AGERR,agxbuse(&xb));
+	agerr(AGERR, "%s", agxbuse(&xb));
 	agxbfree(&xb);
 }
 /* must be here to see flex's macro defns */