The SPICE (aka spice-xpi) plug-in 2.2 for Firefox allows local users to overwrite arbitrary files via a symlink attack on an unspecified log file.
https://bugzilla.redhat.com/show_bug.cgi?id=620356
http://www.vupen.com/english/advisories/2010/2181
http://www.redhat.com/support/errata/RHSA-2010-0651.html