strongSwan 4.2.6 and earlier allows remote attackers to cause a denial of service (daemon crash) via an IKE_SA_INIT message with a large number of NULL values in a Key Exchange payload, which triggers a NULL pointer dereference for the return value of the mpz_export function in the GNU Multiprecision Library (GMP).
http://www.vupen.com/english/advisories/2008/2660
http://www.securitytracker.com/id?1020903
http://www.securityfocus.com/bid/31291
http://secunia.com/advisories/31963