diff -urN strongswan-2.8.9/programs/pluto/asn1.c strongswan-2.8.9_asn1_time/programs/pluto/asn1.c
--- strongswan-2.8.9/programs/pluto/asn1.c	2006-01-04 22:00:43.000000000 +0100
+++ strongswan-2.8.9_asn1_time/programs/pluto/asn1.c	2009-06-18 23:09:39.000000000 +0200
@@ -364,14 +364,20 @@
     {
 	int tz_hour, tz_min;
 
-	sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
+	if (sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min) != 2)
+	{
+	    return 0; /* error in positive timezone offset format */
+	}
 	tz_offset = 3600*tz_hour + 60*tz_min;  /* positive time zone offset */
     }
     else if ((eot = memchr(utctime->ptr, '-', utctime->len)) != NULL)
     {
 	int tz_hour, tz_min;
 
-	sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
+	if (sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min) != 2)
+	{
+	    return 0; /* error in negative timezone offset format */
+	}
 	tz_offset = -3600*tz_hour - 60*tz_min;  /* negative time zone offset */
     }
     else
@@ -383,14 +389,20 @@
 	const char* format = (type == ASN1_UTCTIME)? "%2d%2d%2d%2d%2d":
 						     "%4d%2d%2d%2d%2d";
 
-	sscanf(utctime->ptr, format, &t.tm_year, &t.tm_mon, &t.tm_mday,
-				     &t.tm_hour, &t.tm_min);
+	if (sscanf(utctime->ptr, format, &t.tm_year, &t.tm_mon, &t.tm_mday,
+					 &t.tm_hour, &t.tm_min) != 5)
+	{
+	    return 0; /* error in time st [yy]yymmddhhmm time format */
+	}
     }
 
     /* is there a seconds field? */
     if ((eot - utctime->ptr) == ((type == ASN1_UTCTIME)?12:14))
     {
-	sscanf(eot-2, "%2d", &t.tm_sec);
+	if (sscanf(eot-2, "%2d", &t.tm_sec) != 1)
+	{
+	    return 0; /* error in ss seconds field format */
+	}
     }
     else
     {