A vulnerability in mintplex-labs/anything-llm allows users with manager roles to escalate their privileges to admin roles through a mass assignment issue. The '/admin/system-preferences' API endpoint improperly authorizes manager-level users to modify the 'multi_user_mode' system variable, enabling them to access the '/api/system/enable-multi-user' endpoint and create a new admin user. This issue results from the endpoint accepting a full JSON object in the request body without proper validation of modifiable fields, leading to unauthorized modification of system settings and subsequent privilege escalation.