diff -up isdn4k-utils-CVS-2006-07-20/capi20/convert.c.orig isdn4k-utils-CVS-2006-07-20/capi20/convert.c
--- isdn4k-utils-CVS-2006-07-20/capi20/convert.c.orig	2009-01-19 17:24:26.000000000 +0100
+++ isdn4k-utils-CVS-2006-07-20/capi20/convert.c	2009-01-19 17:25:42.000000000 +0100
@@ -894,8 +894,12 @@ static char *p = 0;
 static void bufprint(char *fmt,...)
 {
 	va_list f;
+	size_t remain = (p >= buf && p < buf+sizeof(buf))
+				  ? buf+sizeof(buf)-p
+				  : 0;
+
 	va_start(f, fmt);
-	vsprintf(p, fmt, f);
+	vsnprintf(p, remain, fmt, f);
 	va_end(f);
 	p += strlen(p);
 }