Xinda Wang, Zhengxu Hou, Yangshijie Zhang, Yanbingren, Jialin Liu, ChenZhuo Zhao, Zhibo Yang, Bin-Bin Yang, Feng Xiao. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2026.

Xinda Wang, Zhengxu Hou, Yangshijie Zhang, Yanbingren, Jialin Liu, ChenZhuo Zhao, Zhibo Yang, Bin-Bin Yang, Feng Xiao. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2026.

Wenqiang Wang, Wen Yujia, Yan Xiao, Zhifeng Chen, Yangshijie Zhang, Peng Chen, Mingbo Yang, Xiaochun Cao. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2026.

Current multi-task adversarial text attacks rely on abundant access to shared internal features and numerous queries, often limited to a single task type.As a result, these attacks are less effective against practical scenarios involving black-box feedback APIs, limited queries, or multiple task types.To bridge this gap, we propose Cluster and Ensemble Multi-task Text Adversarial Attack (CEMA), an effective blackbox attack that exploits the transferability of adversarial texts across different tasks.CEMA simplifies complex multi-task scenarios by using a deep-level substitute model trained in a plug-and-play manner for text classification, enabling attacks without mimicking the victim model.This approach requires only a few queries for training, converting multi-task attacks into classification attacks and allowing attacks across various tasks.CEMA generates multiple adversarial candidates using different text classification methods and selects the one that most effectively attacks substitute models.In experiments involving multi-task models with two, three, or six tasks-spanning classification, translation, summarization, and text-toimage generation-CEMA demonstrates significant attack success with as few as 100 queries.Furthermore, CEMA can target commercial APIs (e.g., Baidu and Google Translate), large language models (e.g., ChatGPT 4o), and image-generation models (e.g., Stable Diffusion V2), showcasing its versatility and effectiveness in real-world applications.