E.200.1. Migration to Version 7.3.21

A dump/restore is not required for those running 7.3.X. However, if you are upgrading from a version earlier than 7.3.13, see Section E.208.

E.200.2. Changes

• Prevent functions in indexes from executing with the privileges of the user running VACUUM, ANALYZE, etc (Tom)

  Functions used in index expressions and partial-index predicates are evaluated whenever a new table entry is made. It has long been understood that this poses a risk of trojan-horse code execution if one modifies a table owned by an untrustworthy user. (Note that triggers, defaults, check constraints, etc. pose the same type of risk.) But functions in indexes pose extra danger because they will be executed by routine maintenance operations such as VACUUM FULL, which are commonly performed automatically under a superuser account. For example, a nefarious user can execute code with superuser privileges by setting up a trojan-horse index definition and waiting for the next routine vacuum. The fix arranges for standard maintenance operations (including VACUUM, ANALYZE, REINDEX, and CLUSTER) to execute as the table owner rather than the calling user, using the same privilege-switching mechanism already used for SECURITY DEFINER functions. To prevent bypassing this security measure, execution of SET SESSION AUTHORIZATION and SET ROLE is now forbidden within a SECURITY DEFINER context. (CVE-2007-6600)

• Require non-superusers who use /contrib/dblink to use only password authentication, as a security measure (Joe)

  The fix that appeared for this in 7.3.20 was incomplete, as it plugged the hole for only some dblink functions. (CVE-2007-6601, CVE-2007-3278)

• Fix potential crash in translate() when using a multibyte database encoding (Tom)

• Make contrib/tablefunc's crosstab() handle NULL rowid as a category in its own right, rather than crashing (Joe)

• Require a specific version of Autoconf to be used when re-generating the configure script (Peter)

  This affects developers and packagers only. The change was made to prevent accidental use of untested combinations of Autoconf and PostgreSQL versions. You can remove the version check if you really want to use a different Autoconf version, but it's your responsibility whether the result works or not.