URIs with invalid %-encoding mishandled by Windows
- October 18, 2007
- Billy Rios, Nate McFeters, Secunia
- Firefox, SeaMonkey, Thunderbird
- Fixed in
- Firefox 188.8.131.52
- SeaMonkey 1.1.5
- Thunderbird 184.108.40.206
On Windows XP with Internet Explorer 7 installed several "web related" URI schemes do not launch the registered protocol-handler if the URI contains an invalid %-encoded sequence. This was initially reported by Billy Rios and Nate McFeters with additional investigation by Secunia. A patch that mitigated the known exploits was shipped with Firefox 220.127.116.11 as described at MFSA 2007-27.
That mitigation did not prevent the incorrect file-handling programs from launching which left some risk. An additional fix has been applied to Firefox 18.104.22.168 that detects when Windows would mishandle these URIs so that the wrong program does not get launched.