This maintenance release fixes several issues with WordPress 3.3, as well as a fix for a cross-site scripting vulnerability that affected version 3.3.
Update your WordPress installation immediately
Here's a list of the fixes
- wp_print_styles() causing mid-page scripts/styles to bleed into admin
- Multi-site Upload Limit Stuck at 50MB
- Wrong widget count on dashboard ryan
- Multisite: No Database Prefix causes strpos(): Empty delimiter
- Never show two flyouts at once
- $userdata not populated properly
- Toolbar shows a warning on a second call
- Unwanted backslash in output
- Users list 'Change role to' allows for changing logged-in Admin role to Subscriber
- current-menu-item and current_page_item classes incorrectly added to custom menu items with no URL value.
- Remove .button styling from _default_wp_die_handler()
- Press This #message is ugly (3.2 to 3.3 regression)
- Quick Edit/Reply missing tabindex causes <tab> to miss Update Comment/Reply button
- Script Loader dies in 3.3 on no-JSON PHP
You really should backup your sites files & database before updating especially if you have made changes to the WordPress core files otherwise your changes will be lost.