Zimbra Collaboration: CVE-2021-34807: Open Redirect vulnerability.

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).