Wu, Zonglin, Yule Xue, Yaoyao Feng, Xiaolong Wang, and Yiren Song. “MCA-Bench: A Multimodal Benchmark for Evaluating CAPTCHA Robustness Against VLM-Based Attacks”. Proceedings of the AAAI Conference on Artificial Intelligence 40, no. 44 (March 14, 2026): 38039–38047. Accessed May 25, 2026. https://ojs.aaai.org/index.php/AAAI/article/view/41141.