functions/imap_general.php in SquirrelMail before 1.4.21 does not properly handle 8-bit characters in passwords, which allows remote attackers to cause a denial of service (disk consumption) by making many IMAP login attempts with different usernames, leading to the creation of many preferences files.
https://exchange.xforce.ibmcloud.com/vulnerabilities/61124
https://bugzilla.redhat.com/show_bug.cgi?id=618096
http://www.vupen.com/english/advisories/2010/2080
http://www.vupen.com/english/advisories/2010/2070
http://www.securityfocus.com/bid/42399
http://www.debian.org/security/2010/dsa-2091
http://support.apple.com/kb/HT5130
http://squirrelmail.org/security/issue/2010-07-23
http://secunia.com/advisories/40971
http://secunia.com/advisories/40964
http://rhn.redhat.com/errata/RHSA-2012-0103.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-August/045383.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-August/045372.html
http://lists.apple.com/archives/security-announce/2012/Feb/msg00000.html