An XSS issue was discovered in Horde Groupware Webmail Edition through 5.2.22 (where the Horde_Text_Filter library before 2.3.7 is used). The attacker can send a plain text e-mail message with JavaScript encoded as a link or email that is mishandled by preProcess in Text2html.php because bespoke use of \\x00\\x00\\x00 and \\x01\\x01\\x01 interferes with XSS defenses.