6 - USN-454-1

A security issue affects the following Ubuntu releases:

Ubuntu 6.06 LTS Ubuntu 6.10 Ubuntu 7.04

This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.

The problem can be corrected by upgrading your system to the following package versions:

Ubuntu 6.06 LTS:
postgresql-8.1 8.1.9-0ubuntu0.6.06

Ubuntu 6.10:
postgresql-8.1 8.1.9-0ubuntu0.6.10

Ubuntu 7.04:
postgresql-8.2 8.2.4-0ubuntu0.7.04

In general, a standard system upgrade is sufficient to effect the necessary changes.

Details follow:

PostgreSQL did not handle the "search_path" configuration option in a secure way for functions declared as "SECURITY DEFINER".

Previously, an attacker could override functions and operators used by the security definer function to execute arbitrary SQL commands with the privileges of the user who created the security definer function. The updated version does not search the temporary table schema for functions and operators any more.

Similarly, an attacker could put forged tables into the temporary table schema to trick the security definer function into using attacker defined data for processing. This was possible because the temporary schema was always implicitly searched first before all other entries in "search_path". The updated version now supports explicit placement of the temporary schema. Please see the HTML documentation or the manual page for "CREATE FUNCTION" for details and an example how to write security definer functions in a secure way.