The FileStore capability in CGI::Session for Ruby before 1.8.1, and possibly PStore, creates files with insecure permissions, which can allow local users to steal session information and hijack sessions.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11128
https://exchange.xforce.ibmcloud.com/vulnerabilities/16996
http://www.mandriva.com/security/advisories?name=MDKSA-2004:128
http://www.gentoo.org/security/en/glsa/glsa-200409-08.xml