The hacker leaked 202 complete records of Adobe employees and 230 of users employed by the US military, government, NASA and a number of educational institutions.
The leaked password have been easily cracked due to the fact that Adobe used the flawed MD5 hashing algorithm to hash them, hasn't salted them and used a single iteration of MD5. The fact that many of them weren't complex enough in the first place only compounded the problem.
The forum site in question has been taken down on Tuesday, and Adobe is in the process of resetting the leaked and compromised passwords, and advising affected users on how to set up a new - and better - password once the forum is back online.
The company has still not shared details on how the breach happened, but claims that other Adobe services - including the Adobe Connect conferencing service itself - were not affected in any way.
UPDATE: It seems that the hacker exploited an SQL injection vulnerability in the server to execute the hack. "Somehow I was able to dump the database in less requests than normal people do," he commented for Dark Reading.