Cursor AI's Composer 2 Model Built on Chinese Moonshot's Kimi
Cursor AI has confirmed that its latest Composer 2 coding model was built on top of Moonshot AI's open-source Kimi 2.5 model, admitting to an oversight in not disclosing the dependency. The revelation, first exposed by an X user on March 22, 2026, sparked questions about transparency and the increasingly global nature of AI development.
The $29.3 billion-valued company behind Cursor admitted the mistake after a developer identified code showing Composer 2 simply used Kimi 2.5 with additional reinforcement learning. The model's ID and tokenizer matched Moonshot's offerings exactly.
"We should have disclosed this upfront. It was a miss on our end," said Aman Sanger, Cursor co-founder, in a statement. He emphasized that the usage was authorized through a commercial partnership with Fireworks AI and complies with Kimi's open-source license.
Moonshot AI confirmed the partnership, congratulating Cursor on the launch and stating that the company had properly sought a license. The Chinese AI lab, backed by Alibaba, has gained significant traction with its Kimi series of models.
The Geopolitical Angle
The timing of the disclosure makes it particularly sensitive. With the US-China AI competition intensifying following DeepSeek's competitive release, American companies relying on Chinese AI technology faces heightened scrutiny.
Cursor had promoted Composer 2 as "frontier-level coding intelligence" without mentioning Moonshot AI or Kimi anywhere in the announcement, blog post, or product interface. Users paying premium prices for what they assumed was Cursor's proprietary technology were unaware they were largely using a Chinese model.
The controversy underscores how deeply interconnected the AI ecosystem has become, with even the most valuable American AI startups depending on open-source models from global providers.