The team has at least outlined what all it changes: in addition to Korean language support, the hotfix is primarily focused on removing an exploit that allowed items to be duplicated as well as a bug that prevented players from dealing damage to enemies. Here's the full list of bug fixes and changes as offered through the Bethesda website.

Bug Fixes

Stability and Performance

• PC: Addressed an issue that could cause the game client to crash after selecting Exit to Desktop.
• PC: Fixed a setting that was left in a debug state. This could allow out of date clients to connect, breaking gameplay.

General

• Exploit: Addressed an exploit that could allow items to be duplicated.

Combat

• Weapons: Addressed an issue that could prevent high-damage and explosive weapons from dealing damage to enemies, or cause enemies to heal immediately after taking damage.