3.2.17 fixes a couple exploits, namely:

(CVE-2014-0081)[https://groups.google.com/forum/#!topic/rubyonrails-security/tfp6gZCtzr4]
(CVE-2014-0082)[https://groups.google.com/forum/#!topic/rubyonrails-security/LMxO_3_eCuc]

A minor version bump like that shouldn't break any existing compatibility.