Can Multimodal Large Language Models Generate and Detect Multimodal Social Media Fake News?

Jiyao Yang, Yang Liu, Zhenyue Qin, Qingyu Chen, Xiuzhen Zhang


Abstract
The rapid advancement of generative AI raises concerns about the misuse of Multimodal LLMs (MLLMs) for large-scale disinformation campaigns on social media. Despite existing research on textual disinformation, a fundamental question remains unanswered: can MLLMs be exploited to fabricate realistic multimodal fake news, and can they reliably detect it? We introduce a multi-agent framework in which a story agent, an image agent, and a critic agent collaborate to produce fake social media posts that plausibly counter true news. We apply the framework to generate over 9,000 paired multimodal news posts across science, health, and entertainment domains, and benchmark 16 open- and closed-source MLLMs for automated detection. We find that most models fall substantially short of human-level accuracy and fail critically on identifying image authenticity. Our research provides a foundation for developing robust defenses against social media fake news. Code and data are available at https://github.com/xiuzhenzhang/Multimodal.
Anthology ID:
2026.findings-emnlp.1454
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
30958–30972
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1454/
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Bibkey:
Cite (ACL):
Jiyao Yang, Yang Liu, Zhenyue Qin, Qingyu Chen, and Xiuzhen Zhang. 2026. Can Multimodal Large Language Models Generate and Detect Multimodal Social Media Fake News?. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 30958–30972, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Can Multimodal Large Language Models Generate and Detect Multimodal Social Media Fake News? (Yang et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.1454.pdf