TrustDLM: Benchmarking Trustworthiness in Diffusion Language Models

Yichuan Mo, Yukun Jiang, Yanbo Shi, Mingjie Li, Michael Backes, Yang Zhang, Yisen Wang


Abstract
Diffusion Language Models (DLMs) are emerging as competitive alternatives to auto-regressive models, but their flexible, any-order decoding may introduce new trustworthiness risks. We present TrustDLM, a comprehensive benchmark for evaluating DLM trustworthiness across safety, privacy, and fairness with multiple categories of static post contexts. Our results show that while DLMs are generally trustworthy with user prompts alone, their alignment degrades noticeably when malicious post-contexts are attached to masked responses. We further find that decoding order and generation length affect evaluation outcomes, while longer contexts do not necessarily induce stronger effects. Finally, we introduce TrustDLM-Auto, the first automatic framework for identifying vulnerable DLM configurations, which reveals substantial weaknesses across models and dimensions. Overall, TrustDLM provides the first trustworthiness evaluation framework specifically designed for DLMs, with practical applicability further validated on closed-source DLMs. Our work will help the community enhance the trustworthiness of DLMs. Our code is available at https://github.com/PKU-ML/TrustDLM.
Anthology ID:
2026.emnlp-main.877
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
20264–20292
Language:
URL:
https://aclanthology.org/2026.emnlp-main.877/
DOI:
Bibkey:
Cite (ACL):
Yichuan Mo, Yukun Jiang, Yanbo Shi, Mingjie Li, Michael Backes, Yang Zhang, and Yisen Wang. 2026. TrustDLM: Benchmarking Trustworthiness in Diffusion Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 20264–20292, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TrustDLM: Benchmarking Trustworthiness in Diffusion Language Models (Mo et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.877.pdf