SafeEraser: Enhancing Safety in Multimodal Large Language Models through Multimodal Machine Unlearning

Junkai Chen, Zhijie Deng, Kening Zheng, Yibo Yan, Shuliang Liu, PeiJun Wu, Peijie Jiang, Jia Liu, Xuming Hu


Abstract
As Multimodal Large Language Models (MLLMs) develop, their potential security issues have become increasingly prominent. **Machine Unlearning (MU)**, as an effective strategy for forgetting specific knowledge in training data, has been widely used in privacy protection. However, *MU for safety in MLLM has yet to be fully explored*. To address this issue, we propose , a safety unlearning benchmark for MLLMs, consisting of 3,000 images and 28.8K VQA pairs. We comprehensively evaluate unlearning methods from two perspectives: **_forget quality_** and **_model utility_**. Our findings show that existing MU methods struggle to maintain model performance while implementing the forget operation and often suffer from **_over-forgetting_**. Hence, we introduce **Prompt Decouple (PD) Loss** to alleviate over-forgetting through decouple prompt during unlearning process. To quantitatively measure over-forgetting mitigated by PD Loss, we propose a new metric called **Safe Answer Refusal Rate (SARR)**. Experimental results demonstrate that combining PD Loss with existing unlearning methods can effectively prevent over-forgetting and achieve a decrease of 79.5% in the SARR metric of LLaVA-7B and LLaVA-13B, while maintaining forget quality and model utility. Our code and dataset will be released upon acceptance. **Warning: This paper contains examples of harmful language and images, and reader discretion is recommended.**
Anthology ID:
2025.findings-acl.731
Volume:
Findings of the Association for Computational Linguistics: ACL 2025
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venues:
Findings | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
14194–14224
Language:
URL:
https://preview.aclanthology.org/ingestion-acl-25/2025.findings-acl.731/
DOI:
Bibkey:
Cite (ACL):
Junkai Chen, Zhijie Deng, Kening Zheng, Yibo Yan, Shuliang Liu, PeiJun Wu, Peijie Jiang, Jia Liu, and Xuming Hu. 2025. SafeEraser: Enhancing Safety in Multimodal Large Language Models through Multimodal Machine Unlearning. In Findings of the Association for Computational Linguistics: ACL 2025, pages 14194–14224, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
SafeEraser: Enhancing Safety in Multimodal Large Language Models through Multimodal Machine Unlearning (Chen et al., Findings 2025)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingestion-acl-25/2025.findings-acl.731.pdf