L3IA Morocco at ArGuard 2026: Intent over Words - Uncovering Implicit Harm in Arabic LLM Prompts

Wiam Saidi, Satori Khalid


Abstract
We present the L3IA Morocco team’s system for shared Task B, designed for large language models and focused on detecting harmful prompts in Arabic. In this context, we define two subtasks: B1 and B2, which refer, respectively, to the binary safe/unsafe classification and the classification of harmfulness into 7 categories. Our system combines three fine-tuned Arabic encoders: AraBERTv2, CAMeLBERTmix, and MARBERT, using soft voting that takes into account the predominant classes. It achieves a macro-F1 score of 0.946 for B1 and 0.902 for B2 during the development phase. In contrast, performance drops to 0.639 for B1 and 0.758 for B2 in the blind test. We demonstrate that this generalization divergence is due to a "unsafe” overprediction bias resulting from an unbalanced training corpus (80% unsafe) and not due to alignment of identifiers or dialects. Finally, we observed a negative result: in zeroshot and few-shot, AceGPT-7B, a generative Arabic LLM, performed poorly compared to fine-tuned encoders (0.38-0.42 on Darija).
Anthology ID:
2026.arabicnlp-sharedtasks.42
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
338–346
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.42/
DOI:
Bibkey:
Cite (ACL):
Wiam Saidi and Satori Khalid. 2026. L3IA Morocco at ArGuard 2026: Intent over Words - Uncovering Implicit Harm in Arabic LLM Prompts. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 338–346, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
L3IA Morocco at ArGuard 2026: Intent over Words - Uncovering Implicit Harm in Arabic LLM Prompts (Saidi & Khalid, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.42.pdf