SquirrelMail is an easy-to-configure, standards-based, webmail package written in PHP. It includes built-in PHP support for the IMAP and SMTP protocols, and pure HTML 4.0 page-rendering for maximum browser-compatibility, strong MIME support, address books, and folder manipulation. The Red Hat SquirrelMail packages provided by the RHSA-2009:0010 advisory introduced a session handling flaw. Users who logged back into SquirrelMail without restarting their web browsers were assigned fixed session identifiers. A remote attacker could make use of that flaw to hijack user sessions. SquirrelMail users should upgrade to this updated package, which contains a patch to correct this issue. As well, all users who used affected versions of SquirrelMail should review their preferences.