Office Viewer in Apple iOS before 6 writes cleartext document data to a temporary file, which might allow local users to bypass a document's intended (1) Data Protection level or (2) encryption state by reading the temporary content.
https://exchange.xforce.ibmcloud.com/vulnerabilities/78709
http://support.apple.com/kb/HT5503
http://lists.apple.com/archives/security-announce/2012/Sep/msg00003.html