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).

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.