In PostgreSQL 9.3.x before 9.3.17, 9.4.x before 9.4.12, 9.5.x before 9.5.7, and 9.6.x before 9.6.3, it was found that the PGREQUIRESSL environment variable was no longer enforcing a SSL/TLS connection to a PostgreSQL server. An active Man-in-the-Middle attacker could use this flaw to strip the SSL/TLS protection from a connection between a client and a server.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:HA:N5.9/CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:NOther