Looking at http://stats.wikimedia.org/archive/squid_reports/2014-01/SquidReportClients.htm there has been recent growth in the percentages for the Mozilla User Agent
Browsers, non mobile
All requests Html pages
Chrome 62,239 M 27.32% 5,025 M 24.13%
Firefox 26,283 M 11.53% 2,487 M 11.94%
MSIE 22,291 M 9.78% 2,371 M 11.39%
Mozilla 16,427 M 7.21% 1,593 M 7.65%
as this is a catchall for unknown browsers I suspect there is some more specific useragent string is not being recognising. This figure has been growing recently in Aug 2012 it was 0.46%, Aug 2013 it was 3.99%.
My guess is it the more recent IE which seem to be using
Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) like Gecko
rather than using something sane like MSIE 11.0 which is does not appear in the stats.
Version: unspecified
Severity: normal