defense 2026

ExpGuard: LLM Content Moderation in Specialized Domains

Minseok Choi 1,2, Dongjin Kim 1,2, Seungbin Yang 1,2, Subin Kim 2, Youngjun Kwak 2, Juyoung Oh 2, Jaegul Choo 1, Jungmin Son 2

0 citations

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Published on arXiv

2603.02588

Prompt Injection

OWASP LLM Top 10 — LLM01

Key Finding

ExpGuard surpasses WildGuard by up to 8.9% in prompt classification and 15.3% in response classification on domain-specific adversarial content across financial, medical, and legal sectors.

ExpGuard

Novel technique introduced


With the growing deployment of large language models (LLMs) in real-world applications, establishing robust safety guardrails to moderate their inputs and outputs has become essential to ensure adherence to safety policies. Current guardrail models predominantly address general human-LLM interactions, rendering LLMs vulnerable to harmful and adversarial content within domain-specific contexts, particularly those rich in technical jargon and specialized concepts. To address this limitation, we introduce ExpGuard, a robust and specialized guardrail model designed to protect against harmful prompts and responses across financial, medical, and legal domains. In addition, we present ExpGuardMix, a meticulously curated dataset comprising 58,928 labeled prompts paired with corresponding refusal and compliant responses, from these specific sectors. This dataset is divided into two subsets: ExpGuardTrain, for model training, and ExpGuardTest, a high-quality test set annotated by domain experts to evaluate model robustness against technical and domain-specific content. Comprehensive evaluations conducted on ExpGuardTest and eight established public benchmarks reveal that ExpGuard delivers competitive performance across the board while demonstrating exceptional resilience to domain-specific adversarial attacks, surpassing state-of-the-art models such as WildGuard by up to 8.9% in prompt classification and 15.3% in response classification. To encourage further research and development, we open-source our code, data, and model, enabling adaptation to additional domains and supporting the creation of increasingly robust guardrail models.


Key Contributions

  • ExpGuard: a domain-specialized guardrail model for harmful prompt/response classification in financial, medical, and legal domains
  • ExpGuardMix dataset: 58,928 labeled prompts with refusal/compliant responses across three specialized domains, including an expert-annotated test set
  • Demonstrated up to 8.9% improvement over WildGuard on prompt classification and 15.3% on response classification on domain-specific adversarial content

🛡️ Threat Analysis


Details

Domains
nlp
Model Types
llmtransformer
Threat Tags
inference_timeblack_box
Datasets
ExpGuardTestExpGuardTrainWildGuard benchmarkeight public safety benchmarks
Applications
llm content moderationfinancial domain safetymedical domain safetylegal domain safety