Parse Server before 8.6.103 and 9.0.0 before 9.10.5-alpha.4 contains an information disclosure vulnerability in LiveQuery. Its subscription hash omits constraints next to a $or operator, including the _Session owner filter and beforeSubscribe constraints, so distinct subscriptions are grouped together. Authenticated clients subscribing with $or queries can receive other users' events, including session tokens usable for impersonation.
Exposure of Sensitive Information to an Unauthorized Actor The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.