The CMB2 WordPress plugin before 2.13.0 does not perform any capability check on one of its AJAX actions, allowing users with a role as low as Subscriber to create arbitrary WordPress options and corrupt existing ones, which can break core site settings and take the site offline.
Exploitation requires the site's or another CMB2 WordPress plugin before 2.13.0 to have declared an oEmbed field, as the CMB2 WordPress plugin before 2.13.0 registers none of its own. The stored value is never attacker-controlled, so the issue does not lead to privilege escalation.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1