Firefox 0.9, Thunderbird 0.6 and other versions before 0.9, and Mozilla 1.7 before 1.7.5 save temporary files with world-readable permissions, which allows local users to read certain web content or attachments that belong to other users, e.g. content that is managed by helper applications such as PDF.
secunia.com/advisories/19823
www.mozilla.org/security/announce/mfsa2005-02.html
www.novell.com/linux/security/advisories/2006_04_25.html
www.redhat.com/support/errata/RHSA-2005-335.html
www.redhat.com/support/errata/RHSA-2005-384.html
bugzilla.mozilla.org/show_bug.cgi?id=251297
exchange.xforce.ibmcloud.com/vulnerabilities/17832
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100056
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9543