Neither Firefox nor the Adobe CDM install any kernel code. The Adobe CDM is, conceptually, the Flash Player's DRM code repackaged to work with Firefox's CDM API. And the Flash Player doesn't need to install new kernel drivers. Studios have different DRM requirements for video quality levels like HD, non-HD, "Studio HD", and "Ultra HD". For higher quality video, studios might require secure hardware path. Even this level, AFAIU, doesn't require new kernel drivers because Windows already has APIs for this.
Neither Firefox nor the Adobe CDM install any kernel code. The Adobe CDM is, conceptually, the Flash Player's DRM code repackaged to work with Firefox's CDM API. And the Flash Player doesn't need to install new kernel drivers. Studios have different DRM requirements for video quality levels like HD, non-HD, "Studio HD", and "Ultra HD". For higher quality video, studios might require secure hardware path. Even this level, AFAIU, doesn't require new kernel drivers because Windows already has APIs for this.