If you mean at the legally recognizable level, I can’t speak for other countries but it can be in Canada. There’s also numerous causes for stuttering so it depends on what you’re working with (e.g. acquired via traumatic brain injury vs. developmental vs. psychogenic). On a personal level, that’s ultimately up to you and how you define disability. While I acknowledge that my stutter is a disability, I don’t always see myself as a person who is disabled. Developmental stuttering is listed in the DSM-5 if that helps to answer your question. Not sure about acquired stuttering though.