Recognition by the UN
Kosovo is not recognized by Russia and China, which are among the 5 memebrsmembers holding veto power in the UN Security Council:
Recognition by Serbia
Finally, Serbia considers Kosovo as its own territory, and therefore have the ability to block its de facto independence, even if such independence was possible de jure. The current autonomous status of Kosovo is governed by Brussels AgreemenAgreement (2013) between Serbia and Kosovo.