Mozilla Firefox OS before 2.2 allows physically proximate attackers to bypass the pass-code protection mechanism and access USB Mass Storage (UMS) media volumes by using the USB interface for a mount operation.
https://bugzilla.mozilla.org/show_bug.cgi?id=1111725
http://www.securityfocus.com/bid/76254
http://www.mozilla.org/security/announce/2015/mfsa2015-74.html