VLM-Guard: Safeguarding Vision-Language Models via Fulfilling Safety Alignment Gap

Fuente: arXiv
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Autores principales: Liu, Qin, Wang, Fei, Xiao, Chaowei, Chen, Muhao
Formato: Preprint
Publicado: 2025
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author Liu, Qin
Wang, Fei
Xiao, Chaowei
Chen, Muhao
author_facet Liu, Qin
Wang, Fei
Xiao, Chaowei
Chen, Muhao
contents The emergence of vision language models (VLMs) comes with increased safety concerns, as the incorporation of multiple modalities heightens vulnerability to attacks. Although VLMs can be built upon LLMs that have textual safety alignment, it is easily undermined when the vision modality is integrated. We attribute this safety challenge to the modality gap, a separation of image and text in the shared representation space, which blurs the distinction between harmful and harmless queries that is evident in LLMs but weakened in VLMs. To avoid safety decay and fulfill the safety alignment gap, we propose VLM-Guard, an inference-time intervention strategy that leverages the LLM component of a VLM as supervision for the safety alignment of the VLM. VLM-Guard projects the representations of VLM into the subspace that is orthogonal to the safety steering direction that is extracted from the safety-aligned LLM. Experimental results on three malicious instruction settings show the effectiveness of VLM-Guard in safeguarding VLM and fulfilling the safety alignment gap between VLM and its LLM component.
format Preprint
id arxiv_https___arxiv_org_abs_2502_10486
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle VLM-Guard: Safeguarding Vision-Language Models via Fulfilling Safety Alignment Gap
Liu, Qin
Wang, Fei
Xiao, Chaowei
Chen, Muhao
Cryptography and Security
Artificial Intelligence
Computer Vision and Pattern Recognition
The emergence of vision language models (VLMs) comes with increased safety concerns, as the incorporation of multiple modalities heightens vulnerability to attacks. Although VLMs can be built upon LLMs that have textual safety alignment, it is easily undermined when the vision modality is integrated. We attribute this safety challenge to the modality gap, a separation of image and text in the shared representation space, which blurs the distinction between harmful and harmless queries that is evident in LLMs but weakened in VLMs. To avoid safety decay and fulfill the safety alignment gap, we propose VLM-Guard, an inference-time intervention strategy that leverages the LLM component of a VLM as supervision for the safety alignment of the VLM. VLM-Guard projects the representations of VLM into the subspace that is orthogonal to the safety steering direction that is extracted from the safety-aligned LLM. Experimental results on three malicious instruction settings show the effectiveness of VLM-Guard in safeguarding VLM and fulfilling the safety alignment gap between VLM and its LLM component.
title VLM-Guard: Safeguarding Vision-Language Models via Fulfilling Safety Alignment Gap
topic Cryptography and Security
Artificial Intelligence
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2502.10486