  The metaverse is a nascent concept that envisions a virtual universe, a
collaborative space where individuals can interact, create, and participate in
a wide range of activities. Privacy in the metaverse is a critical concern as
the concept evolves and immersive virtual experiences become more prevalent.
The metaverse privacy problem refers to the challenges and concerns surrounding
the privacy of personal information and data within Virtual Reality (VR)
environments as the concept of a shared VR space becomes more accessible.
Metaverse will harness advancements from various technologies such as
Artificial Intelligence (AI), Extended Reality (XR), Mixed Reality (MR), and
5G/6G-based communication to provide personalized and immersive services to its
users. Moreover, to enable more personalized experiences, the metaverse relies
on the collection of fine-grained user data that leads to various privacy
issues. Therefore, before the potential of the metaverse can be fully realized,
privacy concerns related to personal information and data within VR
environments must be addressed. This includes safeguarding users' control over
their data, ensuring the security of their personal information, and protecting
in-world actions and interactions from unauthorized sharing. In this paper, we
explore various privacy challenges that future metaverses are expected to face,
given their reliance on AI for tracking users, creating XR and MR experiences,
and facilitating interactions. Moreover, we thoroughly analyze technical
solutions such as differential privacy, Homomorphic Encryption (HE), and
Federated Learning (FL) and discuss related sociotechnical issues regarding
privacy.
