Cross-site scripting (XSS) vulnerability in search.php in SquirrelMail 1.5.1 and earlier, when register_globals is enabled, allows remote attackers to inject arbitrary HTML via the mailbox parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26941
http://www.vupen.com/english/advisories/2007/2732
http://www.securityfocus.com/bid/25159
http://www.securityfocus.com/bid/18700
http://www.mandriva.com/security/advisories?name=MDKSA-2006:147
http://secunia.com/advisories/26235
http://pridels0.blogspot.com/2006/06/squirrelmail-151-xss-vuln.html
http://lists.apple.com/archives/security-announce//2007/Jul/msg00004.html