Roundcube Webmail before 1.1.10, 1.2.x before 1.2.7, and 1.3.x before 1.3.3 allows unauthorized access to arbitrary files on the host's filesystem, including configuration files, as exploited in the wild in November 2017. The attacker must be able to authenticate at the target system with a valid username/password as the attack requires an active session. The issue is related to file-based attachment plugins and _task=settings&_action=upload-display&_from=timezone requests.

rcube_utils.php in Roundcube before 1.1.8 and 1.2.x before 1.2.4 is susceptible to a cross-site scripting vulnerability via a crafted Cascading Style Sheets (CSS) token sequence within an SVG element.

steps/mail/sendmail.inc in Roundcube before 1.1.7 and 1.2.x before 1.2.3, when no SMTP server is configured and the sendmail program is enabled, does not properly restrict the use of custom envelope-from addresses on the sendmail command line, which allows remote authenticated users to execute arbitrary code via a modified HTTP request that sends a crafted e-mail message.

Cross-site scripting (XSS) vulnerability in Horde_Form in Horde Groupware Webmail Edition before 4.0.6 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors, related to email verification. NOTE: Some of these details are obtained from third party information.

Multiple cross-site scripting (XSS) vulnerabilities in Horde IMP before 5.0.18 and Horde Groupware Webmail Edition before 4.0.6 allow remote attackers to inject arbitrary web script or HTML via the (1) composeCache, (2) rtemode, or (3) filename_* parameters to the compose page; (4) formname parameter to the contacts popup window; or (5) IMAP mailbox names. NOTE: some of these details are obtained from third party information.

Cross-site scripting (XSS) vulnerability in mime.php for SquirrelMail before 1.4.3 allows remote attackers to insert arbitrary HTML and script via the content-type mail header, as demonstrated using read_body.php.

Multiple cross-site scripting (XSS) vulnerabilities in Squirrelmail 1.2.10 and earlier allow remote attackers to inject arbitrary HTML or script via (1) the $mailer variable in read_body.php, (2) the $senderNames_part variable in mailbox_display.php, and possibly other vectors including (3) the $event_title variable or (4) the $event_text variable.