Mozilla added the OTS font sanitizing library to prevent downloadable fonts from exposing vulnerabilities in the underlying OS font code. This library mitigates against several issues independently reported by Red Hat Security Response Team member Marc Schoenefeld and Mozilla security researcher Christoph Diehl.
This is now public: http://www.mozilla.org/security/announce/2010/mfsa2010-78.html
This issue has been addressed in following products: Red Hat Enterprise Linux 4 Red Hat Enterprise Linux 5 Red Hat Enterprise Linux 6 Via RHSA-2010:0966 https://rhn.redhat.com/errata/RHSA-2010-0966.html