@inproceedings{fei-etal-2025-semantic,
    title = "Your Semantic-Independent Watermark is Fragile: A Semantic Perturbation Attack against {E}aa{S} Watermark",
    author = "Fei, Zekun  and
      Yi, Biao  and
      Geng, Jianing  and
      Ruiqi, He  and
      Nie, Lihai  and
      Liu, Zheli",
    editor = "Christodoulopoulos, Christos  and
      Chakraborty, Tanmoy  and
      Rose, Carolyn  and
      Peng, Violet",
    booktitle = "Findings of the Association for Computational Linguistics: EMNLP 2025",
    month = nov,
    year = "2025",
    address = "Suzhou, China",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.192/",
    doi = "10.18653/v1/2025.findings-emnlp.192",
    pages = "3600--3614",
    ISBN = "979-8-89176-335-7",
    abstract = "Embedding-as-a-Service (EaaS) has emerged as a successful business pattern but faces significant challenges related to various forms of copyright infringement, particularly the API misuse and model extraction attacks. Various studies have proposed backdoor-based watermarking schemes to protect the copyright of EaaS services. In this paper, we reveal that previous watermarking schemes possess semantic-independent characteristics and propose the Semantic Perturbation Attack (SPA). Our theoretical and experimental analysis demonstrates that this semantic-independent nature makes current watermarking schemes vulnerable to adaptive attacks that exploit semantic perturbation tests to bypass watermark verification. Extensive experimental results across multiple datasets demonstrate that the True Positive Rate (TPR) for identifying watermarked samples under SPA can reach up to more than 95{\%}, rendering watermarks ineffective while maintaining the high utility of the embeddings. In addition, we discuss current potential defense strategies to mitigate SPA. Our code is available at https://github.com/Zk4-ps/EaaS-Embedding-Watermark."
}