Does Unification Come at a Cost? Uni-SafeBench: A Safety Benchmark for Unified Multimodal Large Models

TL;DR

This paper introduces Uni-SafeBench, a comprehensive safety benchmark for Unified Multimodal Large Models, revealing that unification improves capabilities but significantly degrades inherent safety, especially in open-source models.

Contribution

The paper presents Uni-SafeBench and Uni-Judger, new tools for evaluating safety in UMLMs, and provides systematic analysis of safety trade-offs in unified models.

Findings

Unification enhances model capabilities but degrades safety.

Open-source UMLMs have lower safety performance than specialized models.

The benchmark covers six safety categories across seven task types.

Abstract

Unified Multimodal Large Models (UMLMs) integrate understanding and generation capabilities within a single architecture. While this architectural unification, driven by the deep fusion of multimodal features, enhances model performance, it also introduces important yet underexplored safety challenges. Existing safety benchmarks predominantly focus on isolated understanding or generation tasks, failing to evaluate the holistic safety of UMLMs when handling diverse tasks under a unified framework. To address this, we introduce Uni-SafeBench, a comprehensive benchmark featuring a taxonomy of six major safety categories across seven task types. To ensure rigorous assessment, we develop Uni-Judger, a framework that effectively decouples contextual safety from intrinsic safety. Based on comprehensive evaluations across Uni-SafeBench, we uncover that while the unification process enhances model capabilities, it significantly degrades the inherent safety of the underlying LLM. Furthermore, open-source UMLMs exhibit much lower safety performance than multimodal large models specialized for either generation or understanding tasks. We open-source all resources to systematically expose these risks and foster safer AGI development.