Squirrelmail 1.4.15 does not set the secure flag for the session cookie in an https session, which can cause the cookie to be sent in http requests and make it easier for remote attackers to capture this cookie.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10548
https://exchange.xforce.ibmcloud.com/vulnerabilities/45700
http://www.securityfocus.com/bid/31321
http://www.securityfocus.com/archive/1/496601/100/0/threaded
http://www.nabble.com/ANNOUNCE:-SquirrelMail-1.4.16-Released-td19711998.html
http://support.apple.com/kb/HT3438
http://securityreason.com/securityalert/4304
http://secunia.com/advisories/33937
http://lists.opensuse.org/opensuse-security-announce/2009-02/msg00002.html
http://lists.opensuse.org/opensuse-security-announce/2008-12/msg00003.html
http://lists.apple.com/archives/security-announce/2009/Feb/msg00000.html