PgBouncer 1.6.x before 1.6.1, when configured with auth_user, allows remote attackers to gain login access as auth_user via an unknown username.
https://security.gentoo.org/glsa/201701-24
https://pgbouncer.github.io/2015/09/pgbouncer-1-6-1
https://github.com/pgbouncer/pgbouncer/issues/69
https://github.com/pgbouncer/pgbouncer/commit/7ca3e5279d05fceb1e8a043c6f5b6f58dea3ed38
http://www.openwall.com/lists/oss-security/2015/09/05/7
http://comments.gmane.org/gmane.comp.db.postgresql.pgbouncer.general/1251