SquirrelMail 1.4.6 and earlier versions are susceptible to a PHP local file inclusion vulnerability in functions/plugin.php if register_globals is enabled and magic_quotes_gpc is disabled. This allows remote attackers to execute arbitrary PHP code via a URL in the plugins array parameter.
View the template here CVE-2006-2842.yaml
References:
http://squirrelmail.cvs.sourceforge.net/squirrelmail/squirrelmail/functions/global.php?r1=1.27.2.16&r2=1.27.2.17&view=patch&pathrev=SM-1_4-STABLE