Do Not Merge My Model! Safeguarding Open-Source LLMs Against Unauthorized Model Merging

Fuente: arXiv
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Autores principales: Li, Qinfeng, Pan, Miao, Chen, Jintao, Teng, Fu, Shen, Zhiqiang, Su, Ge, Peng, Hao, Zhang, Xuhong
Formato: Preprint
Publicado: 2025
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author Li, Qinfeng
Pan, Miao
Chen, Jintao
Teng, Fu
Shen, Zhiqiang
Su, Ge
Peng, Hao
Zhang, Xuhong
author_facet Li, Qinfeng
Pan, Miao
Chen, Jintao
Teng, Fu
Shen, Zhiqiang
Su, Ge
Peng, Hao
Zhang, Xuhong
contents Model merging has emerged as an efficient technique for expanding large language models (LLMs) by integrating specialized expert models. However, it also introduces a new threat: model merging stealing, where free-riders exploit models through unauthorized model merging. Unfortunately, existing defense mechanisms fail to provide effective protection. Specifically, we identify three critical protection properties that existing methods fail to simultaneously satisfy: (1) proactively preventing unauthorized merging; (2) ensuring compatibility with general open-source settings; (3) achieving high security with negligible performance loss. To address the above issues, we propose MergeBarrier, a plug-and-play defense that proactively prevents unauthorized merging. The core design of MergeBarrier is to disrupt the Linear Mode Connectivity (LMC) between the protected model and its homologous counterparts, thereby eliminating the low-loss path required for effective model merging. Extensive experiments show that MergeBarrier effectively prevents model merging stealing with negligible accuracy loss.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10712
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Do Not Merge My Model! Safeguarding Open-Source LLMs Against Unauthorized Model Merging
Li, Qinfeng
Pan, Miao
Chen, Jintao
Teng, Fu
Shen, Zhiqiang
Su, Ge
Peng, Hao
Zhang, Xuhong
Cryptography and Security
Artificial Intelligence
Model merging has emerged as an efficient technique for expanding large language models (LLMs) by integrating specialized expert models. However, it also introduces a new threat: model merging stealing, where free-riders exploit models through unauthorized model merging. Unfortunately, existing defense mechanisms fail to provide effective protection. Specifically, we identify three critical protection properties that existing methods fail to simultaneously satisfy: (1) proactively preventing unauthorized merging; (2) ensuring compatibility with general open-source settings; (3) achieving high security with negligible performance loss. To address the above issues, we propose MergeBarrier, a plug-and-play defense that proactively prevents unauthorized merging. The core design of MergeBarrier is to disrupt the Linear Mode Connectivity (LMC) between the protected model and its homologous counterparts, thereby eliminating the low-loss path required for effective model merging. Extensive experiments show that MergeBarrier effectively prevents model merging stealing with negligible accuracy loss.
title Do Not Merge My Model! Safeguarding Open-Source LLMs Against Unauthorized Model Merging
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2511.10712