CREATE TRIGGER in PostgreSQL 8.3.x before 8.3.18, 8.4.x before 8.4.11, 9.0.x before 9.0.7, and 9.1.x before 9.1.3 does not properly check the execute permission for trigger functions marked SECURITY DEFINER, which allows remote authenticated users to execute otherwise restricted triggers on arbitrary data by installing the trigger on an attacker-owned table.
http://www.postgresql.org/docs/9.1/static/release-9-1-3.html
http://www.postgresql.org/docs/9.0/static/release-9-0-7.html
http://www.postgresql.org/docs/8.4/static/release-8-4-11.html
http://www.postgresql.org/docs/8.3/static/release-8-3-18.html
http://www.postgresql.org/about/news/1377/
http://www.mandriva.com/security/advisories?name=MDVSA-2012:092
http://www.mandriva.com/security/advisories?name=MDVSA-2012:027
http://www.mandriva.com/security/advisories?name=MDVSA-2012:026
http://www.debian.org/security/2012/dsa-2418
http://secunia.com/advisories/49273
http://secunia.com/advisories/49272
http://rhn.redhat.com/errata/RHSA-2012-0678.html
http://rhn.redhat.com/errata/RHSA-2012-0677.html
http://lists.opensuse.org/opensuse-updates/2012-09/msg00060.html
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705