Sonos api.sonos.com through 2025-04-21, when the /login/v3/oauth endpoint is used, accepts a redirect_uri containing userinfo in the authority component, which is not consistent with RFC 6819 section 5.2.3.5. An authorization code may be sent to an attacker-controlled destination. This might have further implications in conjunction with Decompiling the app revealed a hardcoded secret.
The product defines policy namespaces and makes authorization decisions based on the assumption that a URL is canonical. This can allow a non-canonical URL to bypass the authorization.
If an application defines policy namespaces and makes authorization decisions based on the URL, but it does not require or convert to a canonical URL before making the authorization decision, then it opens the application to attack. For example, if the application only wants to allow access to http://www.example.com/mypage, then the attacker might be able to bypass this restriction using equivalent URLs such as:
Therefore it is important to specify access control policy that is based on the path information in some canonical form with all alternate encodings rejected (which can be accomplished by a default deny rule).