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Main Authors: Hong, Wenjing, Rong, Zhonghua, Wang, Li, Chang, Feng, Zhu, Jian, Tang, Ke, Zhu, Zexuan, Ong, Yew-Soon
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.20122
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author Hong, Wenjing
Rong, Zhonghua
Wang, Li
Chang, Feng
Zhu, Jian
Tang, Ke
Zhu, Zexuan
Ong, Yew-Soon
author_facet Hong, Wenjing
Rong, Zhonghua
Wang, Li
Chang, Feng
Zhu, Jian
Tang, Ke
Zhu, Zexuan
Ong, Yew-Soon
contents Large Language Models (LLMs) have been widely deployed, especially through free Web-based applications that expose them to diverse user-generated inputs, including those from long-tail distributions such as low-resource languages and encrypted private data. This open-ended exposure increases the risk of jailbreak attacks that undermine model safety alignment. While recent studies have shown that leveraging long-tail distributions can facilitate such jailbreaks, existing approaches largely rely on handcrafted rules, limiting the systematic evaluation of these security and privacy vulnerabilities. In this work, we present EvoJail, an automated framework for discovering long-tail distribution attacks via multi-objective evolutionary search. EvoJail formulates long-tail attack prompt generation as a multi-objective optimization problem that jointly maximizes attack effectiveness and minimizes output perplexity, and introduces a semantic-algorithmic solution representation to capture both high-level semantic intent and low-level structural transformations of encryption-decryption logic. Building upon this representation, EvoJail integrates LLM-assisted operators into a multi-objective evolutionary framework, enabling adaptive and semantically informed mutation and crossover for efficiently exploring a highly structured and open-ended search space. Extensive experiments demonstrate that EvoJail consistently discovers diverse and effective long-tail jailbreak strategies, achieving competitive performance with existing methods in both individual and ensemble level.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20122
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Evolving Jailbreaks: Automated Multi-Objective Long-Tail Attacks on Large Language Models
Hong, Wenjing
Rong, Zhonghua
Wang, Li
Chang, Feng
Zhu, Jian
Tang, Ke
Zhu, Zexuan
Ong, Yew-Soon
Cryptography and Security
Artificial Intelligence
Large Language Models (LLMs) have been widely deployed, especially through free Web-based applications that expose them to diverse user-generated inputs, including those from long-tail distributions such as low-resource languages and encrypted private data. This open-ended exposure increases the risk of jailbreak attacks that undermine model safety alignment. While recent studies have shown that leveraging long-tail distributions can facilitate such jailbreaks, existing approaches largely rely on handcrafted rules, limiting the systematic evaluation of these security and privacy vulnerabilities. In this work, we present EvoJail, an automated framework for discovering long-tail distribution attacks via multi-objective evolutionary search. EvoJail formulates long-tail attack prompt generation as a multi-objective optimization problem that jointly maximizes attack effectiveness and minimizes output perplexity, and introduces a semantic-algorithmic solution representation to capture both high-level semantic intent and low-level structural transformations of encryption-decryption logic. Building upon this representation, EvoJail integrates LLM-assisted operators into a multi-objective evolutionary framework, enabling adaptive and semantically informed mutation and crossover for efficiently exploring a highly structured and open-ended search space. Extensive experiments demonstrate that EvoJail consistently discovers diverse and effective long-tail jailbreak strategies, achieving competitive performance with existing methods in both individual and ensemble level.
title Evolving Jailbreaks: Automated Multi-Objective Long-Tail Attacks on Large Language Models
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2603.20122