PgBouncer before 1.5.5 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) by sending a password packet before a startup packet.
www.openwall.com/lists/oss-security/2015/05/22/5
www.securityfocus.com/bid/74751
github.com/pgbouncer/pgbouncer/commit/74d6e5f7de5ec736f71204b7b422af7380c19ac5
github.com/pgbouncer/pgbouncer/commit/edab5be6665b9e8de66c25ba527509b229468573
github.com/pgbouncer/pgbouncer/issues/42
pgbouncer.github.io/changelog.html#pgbouncer-15x
security.gentoo.org/glsa/201701-24