The (1) brin_page_type and (2) brin_metapage_info functions in the pageinspect extension in PostgreSQL before 9.5.x before 9.5.2 allows attackers to bypass intended access restrictions and consequently obtain sensitive server memory information or cause a denial of service (server crash) via a crafted bytea value in a BRIN index page.
http://www.securitytracker.com/id/1035468
http://www.postgresql.org/docs/current/static/release-9-5-2.html