Squirrelmail » Imap General.php : Security Vulnerabilities, CVEs,

The map_yp_alias function in functions/imap_general.php in SquirrelMail before 1.4.19-1 on Debian GNU/Linux, and possibly other operating systems and versions, allows remote attackers to execute arbitrary commands via shell metacharacters in a username string that is used by the ypmatch program. NOTE: this issue exists because of an incomplete fix for CVE-2009-1579.