Rails 1.1.5 (Security release)
Mandatory Security Release (and more). If you’ve never read the comments thread on these release pages, give ‘er a go as there are some interesting comments and DHH is always very active in these threads.
On another note, I really like how insistent the guys are about everyone performing this upgrade:
This is a MANDATORY upgrade for anyone not running on a very recent edge (which isn’t affected by this). If you have a public Rails site, you MUST upgrade to Rails 1.1.5. The security issue is severe and you do not want to be caught unpatched.
You heard the man, get your upgrade on!