An issue was discovered in Zimbra Collaboration Suite 8.8 before 8.8.15 Patch 23 and 9.0 before 9.0.0 Patch 16. An XSS vulnerability exists in the login component of Zimbra Web Client, in which an attacker can execute arbitrary JavaScript by adding executable JavaScript to the loginErrorCode parameter of the login url.

An open redirect vulnerability exists in the /preauth Servlet in Zimbra Collaboration Suite through 9.0. To exploit the vulnerability, an attacker would need to have obtained a valid zimbra auth token or a valid preauth token. Once the token is obtained, an attacker could redirect a user to any URL via isredirect=1&redirectURL= in conjunction with the token data (e.g., a valid authtoken= value).