Multiple cross-site request forgery (CSRF) vulnerabilities in SquirrelMail 1.4.19 and earlier, and NaSMail before 1.7, allow remote attackers to hijack the authentication of unspecified victims via features such as send message and change preferences, related to (1) functions/mailbox_display.php, (2) src/addrbook_search_html.php, (3) src/addressbook.php, (4) src/compose.php, (5) src/folders.php, (6) src/folders_create.php, (7) src/folders_delete.php, (8) src/folders_rename_do.php, (9) src/folders_rename_getname.php, (10) src/folders_subscribe.php, (11) src/move_messages.php, (12) src/options.php, (13) src/options_highlight.php, (14) src/options_identities.php, (15) src/options_order.php, (16) src/search.php, and (17) src/vcard.php.

The map_yp_alias function in functions/imap_general.php in SquirrelMail before 1.4.19-1 on Debian GNU/Linux, and possibly other operating systems and versions, allows remote attackers to execute arbitrary commands via shell metacharacters in a username string that is used by the ypmatch program. NOTE: this issue exists because of an incomplete fix for CVE-2009-1579.

functions/mime.php in SquirrelMail before 1.4.18 does not protect the application's content from Cascading Style Sheets (CSS) positioning in HTML e-mail messages, which allows remote attackers to spoof the user interface, and conduct cross-site scripting (XSS) and phishing attacks, via a crafted message.

The map_yp_alias function in functions/imap_general.php in SquirrelMail before 1.4.18 and NaSMail before 1.7 allows remote attackers to execute arbitrary commands via shell metacharacters in a username string that is used by the ypmatch program.

Session fixation vulnerability in SquirrelMail before 1.4.18 allows remote attackers to hijack web sessions via a crafted cookie.

Multiple cross-site scripting (XSS) vulnerabilities in SquirrelMail before 1.4.18 and NaSMail before 1.7 allow remote attackers to inject arbitrary web script or HTML via vectors involving (1) certain encrypted strings in e-mail headers, related to contrib/decrypt_headers.php; (2) PHP_SELF; and (3) the query string (aka QUERY_STRING).

A certain Red Hat patch for SquirrelMail 1.4.8 sets the same SQMSESSID cookie value for all sessions, which allows remote authenticated users to access other users' folder lists and configuration data in opportunistic circumstances by using the standard webmail.php interface. NOTE: this vulnerability exists because of an incorrect fix for CVE-2008-3663.

Cross-site scripting (XSS) vulnerability in SquirrelMail before 1.4.17 allows remote attackers to inject arbitrary web script or HTML via a crafted hyperlink in an HTML part of an e-mail message.

Squirrelmail 1.4.15 does not set the secure flag for the session cookie in an https session, which can cause the cookie to be sent in http requests and make it easier for remote attackers to capture this cookie.

SquirrelMail 1.4.11 and 1.4.12, as distributed on sourceforge.net before 20071213, has been externally modified to create a Trojan Horse that introduces a PHP remote file inclusion vulnerability, which allows remote attackers to execute arbitrary code.