(RHSA-2010:0556) Critical: firefox security update

Mozilla Firefox is an open source web browser. XULRunner provides the XUL
Runtime environment for Mozilla Firefox.

An invalid free flaw was found in Firefox’s plugin handler. Malicious web
content could result in an invalid memory pointer being freed, causing Firefox
to crash or, potentially, execute arbitrary code with the privileges of the user
running the Firefox application. (CVE-2010-2755)

All Firefox users should upgrade to these updated packages, which contain a
backported patch that corrects this issue. After installing the update, Firefox
must be restarted for the changes to take effect.