A flaw was found in Feast. The system improperly deserializes user-defined functions (UDFs) stored in its registry, which are serialized using the 'dill' library. This allows a remote attacker to store a malicious UDF, leading to unauthenticated arbitrary code execution on the feature server in default configurations. An authenticated attacker can also achieve arbitrary code execution on the registry server by bypassing authorization checks during deserialization. This vulnerability can result in cross-tenant data access and lateral movement within the system.
Configure Feast to enforce auth.type: kubernetes in the operator-generated configuration and deny registry writes by default. This measure limits the attack surface by requiring proper authentication and authorization for registry modifications, preventing the deserialization of malicious user-defined functions.