The XPInstall installer in Mozilla Firefox before the Preview Release, Mozilla before 1.7.3, and Thunderbird before 0.8 sets insecure permissions for certain installed files within xpi packages, which could allow local users to overwrite arbitrary files or execute arbitrary code.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11668
https://exchange.xforce.ibmcloud.com/vulnerabilities/17375
http://www.securityfocus.com/bid/11192
http://www.redhat.com/support/errata/RHSA-2005-323.html
http://www.novell.com/linux/security/advisories/2004_36_mozilla.html
http://www.mozilla.org/projects/security/known-vulnerabilities.html#mozilla1.7.3
http://www.kb.cert.org/vuls/id/653160
http://security.gentoo.org/glsa/glsa-200409-26.xml
http://secunia.com/advisories/12526/