Vulnerable component: Roundcube
CVSSv3 score: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:H/RL:O/RC:C
CWE-ID: CWE-200 - Information Exposure
The vulnerability allows a remote authenticated attacker to obtain potentially sensitive information on the target system.
The weakness exists due to insufficient validation of file-based attachment plugins and _task=settings&_action=upload-display&_from=timezone requests. A remote attacker can modify the login form and submit it with valid credentials (username/password) of an email account, send a specially crafted HTTP request and gain unauthorized access to arbitrary files on the host's filesystem, including configuration files of Roundcube.
Note: the vulnerability is being actively exploited.