Double free vulnerability in PostgreSQL before 9.0.20, 9.1.x before 9.1.16, 9.2.x before 9.2.11, 9.3.x before 9.3.7, and 9.4.x before 9.4.2 allows remote attackers to cause a denial of service (crash) by closing an SSL session at a time when the authentication timeout will expire during the session shutdown sequence.