Plane is an open-source project management tool. Prior to 1.4.0, a Project Member with role 15 can send a PATCH request to the project-member update endpoint at /api/workspaces/{workspace_slug}/projects/{project_id}/members/{member_pk}/ to change another users project role. The role-update logic blocks only a new role higher than the requesters role, so assigning the equal Member role bypasses the insufficient validation and promotes a Project Guest with role 5 to Member without Project Admin approval. This unauthorized promotion grants the guest the additional project capabilities associated with the Member role and allows a regular member to bypass project governance controls. This issue is fixed in 1.4.0.
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.