The PL/Tcl implementation in PostgreSQL 7.4 before 7.4.29, 8.0 before 8.0.25, 8.1 before 8.1.21, 8.2 before 8.2.17, 8.3 before 8.3.11, 8.4 before 8.4.4, and 9.0 Beta before 9.0 Beta 2 loads Tcl code from the pltcl_modules table regardless of the table's ownership and permissions, which allows remote authenticated users, with database-creation privileges, to execute arbitrary Tcl code by creating this table and inserting a crafted Tcl script.