Microsoft and Xbox owners are both reporting login issues on the Xbox One, Xbox 360 and other various devices. Login is not the only part of Xbox Live that is affected; the Xbox services have also been limited.
Microsoft's support page has listed TV, Music and Video services to be limited as well as the core services across the Xbox One, Xbox 360 and "other devices." The YouTube app, Xfinity on Demand app, and Netflix app are also detailed to be suffering limited service.
TeamBudyBear, a hacker group that looks to teach "the community about information security and account safeguarding," is claiming responsibility for Xbox Live's current issues. Whether or not they are truly the cause of Xbox Live's current condition has not been confirmed or revealed by Microsoft, nor have they claimed that they are suffering a DDoS attack — an attack that should be familiar to those that attemped to login to Xbox Live or PSN on December 25th.
This hacking group has claimed to hack into gamer's Xbox gamertags, Instagram accounts, Twitch and more.