LobeChat through 2.2.9 contains a broken access control vulnerability in the retrieval-augmented-generation semantic search functionality that allows authenticated attackers to access other users' data by exploiting missing user-identifier predicates in the chunk model semanticSearch method. Attackers can supply arbitrary victim file or knowledge-base identifiers through the chunk retrieval and chat knowledge-base paths to retrieve text content, file names, and metadata belonging to other users.