Pan Zhou
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2026
CrowdSelect: SyntheticInstruction Data Selection with Multi-LLM Wisdom
Yisen Li | Lingfeng Yang | Wenxuan Shen | Pan Zhou | Yao Wan | Weiwei Lin | Dongping Chen
Findings of the Association for Computational Linguistics: EACL 2026
Yisen Li | Lingfeng Yang | Wenxuan Shen | Pan Zhou | Yao Wan | Weiwei Lin | Dongping Chen
Findings of the Association for Computational Linguistics: EACL 2026
Distilling advanced Large Language Models’ instruction-following capabilities into smaller models using a selected subset has become a mainstream approach in model training. While existing synthetic instruction data selection strategies rely mainly on single-dimensional signals (i.e., reward scores, model perplexity), they fail to capture the complexity of instruction-following across diverse fields. Therefore, we investigate more diverse signals to capture comprehensive instruction-response pair characteristics and propose three foundational metrics that leverage Multi-LLMs wisdom, informed by (1) diverse LLM responses and (2) reward model assessment. Building upon base metrics, we propose CrowdSelect, an integrated metric incorporating a clustering-based approach to maintain response diversity. Our comprehensive experiments demonstrate that our foundation metrics consistently improve performance across 4 base models on MT-bench and Arena-Hard. CrowdSelect, efficiently incorporating all metrics, achieves state-of-the-art performance in both Full and LoRA fine-tuning, showing improvements of 4.81% on Arena-Hard and 11.1% on MT-bench with Llama-3.2-3b-instruct. We hope our findings will bring valuable insights for future research in this direction.
LearnerCoMPASS: Intelligent Tutoring System with Dynamic Cognitive Diagnosis and Multi-Model Path Planning
Ziji Sheng | Guiyao Tie | Weidong Wang | Pan Zhou | Daizong Liu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Ziji Sheng | Guiyao Tie | Weidong Wang | Pan Zhou | Daizong Liu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Existing adaptive learning systems struggle to simultaneously achieve deep personalization, dynamic adaptability, and content trustworthiness, particularly in logically rigorous STEM fields where Large Language Models (LLMs) are prone to “hallucination”. This paper introduces LearnerCoMPASS (Cognitive Multi-model Planning Adaptive System), an integrated, end-to-end framework for adaptive learning. At its core, the framework features a novel multi-model path planning algorithm that orchestrates and fuses the outputs of heterogeneous LLM experts to generate and optimize learning sequences. To enable deep personalization, we design a dynamic cognitive diagnosis module that employs an innovative encoder-decoder architecture to generate precise, multi-dimensional cognitive state vectors for learners. To ensure trustworthiness, the system leverages an adaptively constructed dynamic knowledge graph and a Graph-RAG mechanism to provide factual anchors and logical constraints for LLM reasoning, thereby mitigating hallucinations. Extensive experiments demonstrate that LearnerCoMPASS significantly outperforms state-of-the-art baselines in generating high-quality personalized learning paths. Furthermore, ablation studies validate the critical contributions of our dynamic cognitive diagnosis and multi-model planning components.
SafeAgent: Safeguarding LLM Agents via an Automated Risk Simulator
Xueyang Zhou | Weidong Wang | Lin Lu | Jiawen Shi | Guiyao Tie | Xu Yongtian | Lixing Chen | Pan Zhou | Neil Zhenqiang Gong | Lichao Sun
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Xueyang Zhou | Weidong Wang | Lin Lu | Jiawen Shi | Guiyao Tie | Xu Yongtian | Lixing Chen | Pan Zhou | Neil Zhenqiang Gong | Lichao Sun
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
LLM-based agents are rapidly being deployed in real-world applications (e.g., digital assistants and customer service), making safety a critical concern. However, in multi-turn, tool-augmented settings, dynamic user interactions, external tool use, and unintended harmful behaviors make robust safety assurance challenging. To address these challenges, we propose SafeAgent, a framework that improves agent safety through fully automated synthetic data generation. SafeAgent introduces (1) an open and extensible threat model OTS that decomposes agent risk into instruction-, context-, and action-induced sources to ground safety analysis and alignment; and (2) an automated pipeline that instantiates OTS to surface scenario-specific failure modes, stress-test agents, and generate self-reflective safe responses—without hazardous real-world data collection. We evaluate SafeAgent on two safety benchmarks and one real-world terminal task. Across four widely used open-source models, SafeAgent improves safety performance by 45% on average and delivers a 28.91% gain on the real-world task, outperforming state-of-the-art closed-source models. These results highlight the practical advancement and scalability of SafeAgent in building safer LLM agents for real-world deployment.
2025
Misalignment Attack on Text-to-Image Models via Text Embedding Optimization and Inversion
Zhijie Du | Daizong Liu | Pan Zhou
Findings of the Association for Computational Linguistics: EMNLP 2025
Zhijie Du | Daizong Liu | Pan Zhou
Findings of the Association for Computational Linguistics: EMNLP 2025
Text embedding serves not only as a core component of modern NLP models but also plays a pivotal role in multimodal systems such as text-to-image (T2I) models, significantly facilitating user-friendly image generation through natural language instructions. However, with the convenience being brought, it also introduces additional risks. Misalignment issues of T2I models, whether caused by unintentional user inputs or targeted attacks, can negatively impact the reliability and ethics of these models. In this paper, we introduce TEOI, which fully considers the continuity and distribution characteristics of text embeddings. The framework directly optimizes the embeddings using gradient-based methods and then inverts them to obtain misaligned prompts of discrete tokens. The TEOI framework is capable of conducting both text-modal and multimodal misalignment attacks, revealing the vulnerabilities of multimodal models that rely on text embeddings. Our work highlights the potential risks associated with embedding-based text representations in prevailing T2I models and provides a foundation for further research into robust and secure text-to-image generation systems.
The Impact of Large Language Models in Academia: from Writing to Speaking
Mingmeng Geng | Caixi Chen | Yanru Wu | Yao Wan | Pan Zhou | Dongping Chen
Findings of the Association for Computational Linguistics: ACL 2025
Mingmeng Geng | Caixi Chen | Yanru Wu | Yao Wan | Pan Zhou | Dongping Chen
Findings of the Association for Computational Linguistics: ACL 2025
Large language models (LLMs) are increasingly impacting human society, particularly in textual information. Based on more than 30,000 papers and 1,000 presentations from machine learning conferences, we examined and compared the words used in writing and speaking, representing the first large-scale study of how LLMs influence the two main modes of verbal communication and expression within the same group of people. Our empirical results show that LLM-style words such as significant have been used more frequently in abstracts and oral presentations. The implicit impact on human expression like writing and speaking is beginning to emerge and is likely to grow in the future. We take the first step in building an automated monitoring platform to record its longitudinal changes to call attention to the implicit influence and ripple effect of LLMs on human society.
Learning from Few Samples: A Novel Approach for High-Quality Malcode Generation
Haijian Ma | Daizong Liu | Xiaowen Cai | Pan Zhou | Yulai Xie
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Haijian Ma | Daizong Liu | Xiaowen Cai | Pan Zhou | Yulai Xie
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Intrusion Detection Systems (IDS) play a crucial role in network security defense. However, a significant challenge for IDS in training detection models is the shortage of adequately labeled malicious samples. To address these issues, this paper introduces a novel semi-supervised framework GANGRL-LLM, which integrates Generative Adversarial Networks (GANs) with Large Language Models (LLMs) to enhance malicious code generation and SQL Injection (SQLi) detection capabilities in few-sample learning scenarios. Specifically, our framework adopts a collaborative training paradigm where: (1) the GAN-based discriminator improves malicious pattern recognition through adversarial learning with generated samples and limited real samples; and (2) the LLM-based generator refines the quality of malicious code synthesis using reward signals from the discriminator. The experimental results demonstrate that even with a limited number of labeled samples, our training framework is highly effective in enhancing both malicious code generation and detection capabilities. This dual enhancement capability offers a promising solution for developing adaptive defense systems capable of countering evolving cyber threats.
Merger-as-a-Stealer: Stealing Targeted PII from Aligned LLMs with Model Merging
Lin Lu | Zhigang Zuo | Ziji Sheng | Pan Zhou
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Lin Lu | Zhigang Zuo | Ziji Sheng | Pan Zhou
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Model merging has emerged as a promising approach for updating large language models (LLMs) by integrating multiple domain-specific models into a cross-domain merged model. Despite its utility and plug-and-play nature, unmonitored mergers can introduce significant security vulnerabilities, such as backdoor attacks and model merging abuse. In this paper, we identify a novel and more realistic attack surface where a malicious merger can extract targeted personally identifiable information (PII) from an aligned model with model merging. Specifically, we propose Merger-as-a-Stealer, a two-stage framework to achieve this attack: First, the attacker fine-tunes a malicious model to force it to respond to any PII-related queries. The attacker then uploads this malicious model to the model merging conductor and obtains the merged model. Second, the attacker inputs direct PII-related queries to the merged model to extract targeted PII. Extensive experiments demonstrate that Merger-as-a-Stealer successfully executes attacks against various LLMs and model merging methods across diverse settings, highlighting the effectiveness of the proposed framework. Given that this attack enables character-level extraction for targeted PII without requiring any additional knowledge from the attacker, we stress the necessity for improved model alignment and more robust defense mechanisms to mitigate such threats.
Stealing Training Data from Large Language Models in Decentralized Training through Activation Inversion Attack
Chenxi Dai | Lin Lu | Pan Zhou
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Chenxi Dai | Lin Lu | Pan Zhou
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Decentralized training has become a resource-efficient framework to democratize the training of large language models (LLMs). However, the privacy risks associated with this framework, particularly due to the potential inclusion of sensitive data in training datasets, remain unexplored. This paper identifies a novel and realistic attack surface: the privacy leakage from training data in decentralized training, and proposes activation inversion attack (AIA) for the first time. AIA first constructs a shadow dataset comprising text labels and corresponding activations using public datasets. Leveraging this dataset, an attack model can be trained to reconstruct the training data from activations in victim decentralized training. We conduct extensive experiments on various LLMs and publicly available datasets to demonstrate the susceptibility of decentralized training to AIA. These findings highlight the urgent need to enhance security measures in decentralized training to mitigate privacy risks in training LLMs.
Merge Hijacking: Backdoor Attacks to Model Merging of Large Language Models
Zenghui Yuan | Yangming Xu | Jiawen Shi | Pan Zhou | Lichao Sun
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Zenghui Yuan | Yangming Xu | Jiawen Shi | Pan Zhou | Lichao Sun
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Model merging for Large Language Models (LLMs) directly fuses the parameters of different models finetuned on various tasks, creating a unified model for multi-domain tasks. However, due to potential vulnerabilities in models available on open-source platforms, model merging is susceptible to backdoor attacks. In this paper, we propose Merge Hijacking, the first backdoor attack targeting model merging in LLMs. The attacker constructs a malicious upload model and releases it. Once a victim user merges it with any other models, the resulting merged model inherits the backdoor while maintaining utility across tasks. Merge Hijacking defines two main objectives—effectiveness and utility—and achieves them through four steps. Extensive experiments demonstrate the effectiveness of our attack across different models, merging algorithms, and tasks. Additionally, we show that the attack remains effective even when merging real-world models. Moreover, our attack demonstrates robustness against two inference-time defenses (Paraphrasing and CLEANGEN) and one training-time defense (Fine-pruning).
2024
Virtual Context Enhancing Jailbreak Attacks with Special Token Injection
Yuqi Zhou | Lin Lu | Ryan Sun | Pan Zhou | Lichao Sun
Findings of the Association for Computational Linguistics: EMNLP 2024
Yuqi Zhou | Lin Lu | Ryan Sun | Pan Zhou | Lichao Sun
Findings of the Association for Computational Linguistics: EMNLP 2024
Jailbreak attacks on large language models (LLMs) involve inducing these models to generate harmful content that violates ethics or laws, posing a significant threat to LLM security. Current jailbreak attacks face two main challenges: low success rates due to defensive measures and high resource requirements for crafting specific prompts. This paper introduces Virtual Context, which leverages special tokens, previously overlooked in LLM security, to improve jailbreak attacks. Virtual Context addresses these challenges by significantly increasing the success rates of existing jailbreak methods and requiring minimal background knowledge about the target model, thus enhancing effectiveness in black-box settings without additional overhead. Comprehensive evaluations show that Virtual Context-assisted jailbreak attacks can improve the success rates of four widely used jailbreak methods by approximately 40% across various LLMs. Additionally, applying Virtual Context to original malicious behaviors still achieves a notable jailbreak effect. In summary, our research highlights the potential of special tokens in jailbreak attacks and recommends including this threat in red-teaming testing to comprehensively enhance LLM security.
CodeIP: A Grammar-Guided Multi-Bit Watermark for Large Language Models of Code
Batu Guan | Yao Wan | Zhangqian Bi | Zheng Wang | Hongyu Zhang | Pan Zhou | Lichao Sun
Findings of the Association for Computational Linguistics: EMNLP 2024
Batu Guan | Yao Wan | Zhangqian Bi | Zheng Wang | Hongyu Zhang | Pan Zhou | Lichao Sun
Findings of the Association for Computational Linguistics: EMNLP 2024
Large Language Models (LLMs) have achieved remarkable progress in code generation. It now becomes crucial to identify whether the code is AI-generated and to determine the specific model used, particularly for purposes such as protecting Intellectual Property (IP) in industry and preventing cheating in programming exercises. To this end, several attempts have been made to insert watermarks into machine-generated code. However, existing approaches are limited to inserting only a single bit of information. In this paper, we introduce CodeIP, a novel multi-bit watermarking technique that embeds additional information to preserve crucial provenance details, such as the vendor ID of an LLM, thereby safeguarding the IPs of LLMs in code generation. Furthermore, to ensure the syntactical correctness of the generated code, we propose constraining the sampling process for predicting the next token by training a type predictor. Experiments conducted on a real-world dataset across five programming languages demonstrate the effectiveness of CodeIP in watermarking LLMs for code generation while maintaining the syntactical correctness of code.
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Co-authors
- Lin Lu 4
- Lichao Sun 4
- Daizong Liu 3
- Yao Wan 3
- Dongping Chen 2
- Ziji Sheng 2
- Jiawen Shi 2
- Guiyao Tie 2
- Weidong Wang 2
- Zhangqian Bi 1
- Xiaowen Cai 1
- Caixi Chen 1
- Lixing Chen 1
- Chenxi Dai 1
- Zhijie Du 1
- Mingmeng Geng 1
- Neil Zhenqiang Gong 1
- Batu Guan 1
- Yisen Li 1
- Weiwei Lin 1
- Haijian Ma 1
- Wenxuan Shen 1
- Ryan Sun 1
- Zheng Wang 1
- Yanru Wu 1
- Yulai Xie 1
- Yangming Xu 1
- Lingfeng Yang 1
- Xu Yongtian 1
- Zenghui Yuan 1
- Hongyu Zhang 1
- Xueyang Zhou 1
- Yuqi Zhou 1
- Zhigang Zuo 1