** DISPUTED **  PHP remote file inclusion vulnerability in functions/plugin.php in SquirrelMail 1.4.6 and earlier, if register_globals is enabled and magic_quotes_gpc is disabled, allows remote attackers to execute arbitrary PHP code via a URL in the plugins array parameter.  NOTE: this issue has been disputed by third parties, who state that Squirrelmail provides prominent warnings to the administrator when register_globals is enabled.  Since the varieties of administrator negligence are uncountable, perhaps this type of issue should not be included in CVE.  However, the original developer has posted a security advisory, so there might be relevant real-world environments under which this vulnerability is applicable.