OpenCTI is an open-source cyber threat intelligence platform. In versions starting from 6.4.8 to before 6.4.10, the allow/deny lists can be bypassed, allowing a user to change attributes that are intended to be unmodifiable by the user. It is possible to toggle the external flag on/off and change the own token value for a user. It is also possible to edit attributes that are not in the allow list, such as otpqr and otpactivated. If external users exist in the OpenCTI setup and the information about these users identities is sensitive, the above vulnerabilities can be used to enumerate existing user accounts as a standard low privileged user. This issue has been patched in version 6.4.10.