OpenProject is an open-source, web-based project management software. Prior to version 16.6.2, OpenProject’s unauthenticated password-change endpoint (/account/change_password) was not protected by the same brute-force safeguards that apply to the normal login form. In affected versions, an attacker who can guess or enumerate user IDs can send unlimited password-change requests for a given account without triggering lockout or other rate-limiting controls. This allows automated password-guessing (e.g., with wordlists of common passwords) against valid accounts. Successful guessing results in full account compromise for the targeted user and, depending on that user’s role, can lead to further privilege escalation inside the application. This issue has been patched in version 16.6.2. Those who are unable to upgrade may apply the patch manually.