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Main Authors: Qi, Peigui, Tang, Kunsheng, Yu, Yanpu, Wu, Jialin, Song, Yide, Zhou, Wenbo, Huang, Zhicong, Hong, Cheng, Zhang, Weiming, Yu, Nenghai
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.06502
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_version_ 1866910110245191680
author Qi, Peigui
Tang, Kunsheng
Yu, Yanpu
Wu, Jialin
Song, Yide
Zhou, Wenbo
Huang, Zhicong
Hong, Cheng
Zhang, Weiming
Yu, Nenghai
author_facet Qi, Peigui
Tang, Kunsheng
Yu, Yanpu
Wu, Jialin
Song, Yide
Zhou, Wenbo
Huang, Zhicong
Hong, Cheng
Zhang, Weiming
Yu, Nenghai
contents Vision-Language Models (VLMs) face significant safety vulnerabilities from malicious prompt attacks due to weakened alignment during visual integration. Existing defenses suffer from efficiency and robustness. To address these challenges, we first propose the Multimodal Aggregated Feature Extraction (MAFE) framework that enables CLIP to handle long text and fuse multimodal information into unified representations. Through empirical analysis of MAFE-extracted features, we discover distinct distributional patterns between benign and malicious prompts. Building upon this finding, we develop VLMShield, a lightweight safety detector that efficiently identifies multimodal malicious attacks as a plug-and-play solution. Extensive experiments demonstrate superior performance across multiple dimensions, including robustness, efficiency, and utility. Through our work, we hope to pave the way for more secure multimodal AI deployment. Code is available at [this https URL](https://github.com/pgqihere/VLMShield).
format Preprint
id arxiv_https___arxiv_org_abs_2604_06502
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle VLMShield: Efficient and Robust Defense of Vision-Language Models against Malicious Prompts
Qi, Peigui
Tang, Kunsheng
Yu, Yanpu
Wu, Jialin
Song, Yide
Zhou, Wenbo
Huang, Zhicong
Hong, Cheng
Zhang, Weiming
Yu, Nenghai
Machine Learning
I.2; K.7
Vision-Language Models (VLMs) face significant safety vulnerabilities from malicious prompt attacks due to weakened alignment during visual integration. Existing defenses suffer from efficiency and robustness. To address these challenges, we first propose the Multimodal Aggregated Feature Extraction (MAFE) framework that enables CLIP to handle long text and fuse multimodal information into unified representations. Through empirical analysis of MAFE-extracted features, we discover distinct distributional patterns between benign and malicious prompts. Building upon this finding, we develop VLMShield, a lightweight safety detector that efficiently identifies multimodal malicious attacks as a plug-and-play solution. Extensive experiments demonstrate superior performance across multiple dimensions, including robustness, efficiency, and utility. Through our work, we hope to pave the way for more secure multimodal AI deployment. Code is available at [this https URL](https://github.com/pgqihere/VLMShield).
title VLMShield: Efficient and Robust Defense of Vision-Language Models against Malicious Prompts
topic Machine Learning
I.2; K.7
url https://arxiv.org/abs/2604.06502