Security researcher Holger Fuhrmannek reported that a malicious Graphite "smart font" could circumvent the validation of internal instruction parameters in the Graphite 2 library using special CNTXT_ITEM instructions. This could result in arbitrary code execution. This issue affected Graphite 2 version 1.2.4, which was used in the Firefox ESR branch. To address this issue and other security vulnerabilities recently disclosed by Cisco Talos affecting this version of the library, Firefox ESR has been updated to version 1.3.5, the same one used in Firefox 44. External Reference: https://www.mozilla.org/security/announce/2016/mfsa2016-14.html
This issue has been addressed in the following products: Red Hat Enterprise Linux 5 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Via RHSA-2016:0197 https://rhn.redhat.com/errata/RHSA-2016-0197.html
This issue has been addressed in thunderbird via the following security advisory: https://rhn.redhat.com/errata/RHSA-2016-0258.html