I don’t know all the details, but WordPress 2.1.2 has just been released. From what I understand, if you upgraded to 2.1.1 (it came out a week or so ago), it is recommended that you upgrade as soon as possible.

The download is available at the WordPress download page.

I don’t have a list yet of changed files, but as soon as I see one, I’ll post it here.

UPDATE:

Here’s a little more information on the sudden release of WP 2.1.1. It seems a couple of the release files for WP 2.1.1 were changed by an unscrupulous person. So, this release only affects you if you downloaded and installed WP 2.1.1 within the last week. It is important, though, if you are still on 2.1.0, that you do the upgrade. This from the WordPress Blog:

Longer explanation: This morning we received a note to our security mailing address about unusual and highly exploitable code in WordPress. The issue was investigated, and it appeared that the 2.1.1 download had been modified from its original code. We took the website down immediately to investigate what happened.

It was determined that a cracker had gained user-level access to one of the servers that powers wordpress.org, and had used that access to modify the download file. We have locked down that server for further forensics, but at this time it appears that the 2.1.1 download was the only thing touched by the attack. They modified two files in WP to include code that would allow for remote PHP execution.

What some people do for enjoyment…