PostgreSQL contains a flaw that may allow an attacker to gain access to unauthorized privileges. The issue is triggered when the PL/perl and PL/Tcl implementations fail to properly prevent different SQL users from executing scripts in the same session, allowing a remote authenticated attacker to use crafted script code in a SECURITY DEFINER function to gain elevated privileges, allowing the execution of SQL code with the privileges of the initial user.
Upgrade to version 9.0.1, 8.4.5, 8.3.12, 8.2.18, 8.1.22, 8.0.26, or 7.4.30 or higher, as they have been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.