Navidrome is an open source web-based music collection server and streamer. The issue is a parameter tampering vulnerability where an attacker can manipulate parameter values in the HTTP requests, allowing them to impersonate another user. This can be done by changing the parameter values in the body, and the attacker must be able to intercept HTTP traffic for this attack. Each known user is impacted, and an attacker can obtain the `ownerId` from shared playlist information, meaning every user who has shared a playlist is also impacted, as they can be impersonated.