SquirrelMail is a standards-based webmail package written in PHP4.
A local file disclosure flaw was found in the way SquirrelMail loads plugins. In SquirrelMail 1.4.6 or earlier, if register_globals is on and magic_quotes_gpc is off, it became possible for an unauthenticated remote user to view the contents of arbitrary local files the web server has read-access to. This configuration is neither default nor safe, and configuring PHP with the register_globals set on is dangerous and not recommended. (CVE-2006-2842)
Users of SquirrelMail should upgrade to this erratum package, which contains a backported patch to correct this issue.