Anysphere, Inc. (Cursor)—Cursor maker Anysphere shipped Composer 2 as an in-house model without disclosing it was built on Moonshot AI's open-weight Kimi K2.5
Anysphere launched 'Composer 2' inside its Cursor code editor on March 19, 2026, marketing it as frontier in-house coding intelligence without disclosing its base model. Within days, a developer identified the underlying model fingerprint as Moonshot AI's open-weight Kimi K2.5, and Moonshot's head of pretraining publicly accused Cursor of violating Kimi's modified-MIT license (which requires prominent 'Kimi K2.5' UI attribution and licensing fees above $20M in monthly revenue or 100M MAU -- thresholds Cursor's roughly $2B annualized revenue clearly exceeds) without paying fees. Cursor VP Lee Robinson and co-founder Aman Sanger acknowledged Composer 2 started from the open-source Kimi base, with Sanger calling the lack of disclosure in Cursor's launch blog post 'a miss.' Moonshot separately stated Cursor's use came through an authorized commercial partnership with Fireworks AI, muddying the licensing-violation claim.
Scoring Impact
| Topic | Direction | Relevance | Contribution |
|---|---|---|---|
| Corporate Transparency | -against | primary | -1.00 |
| Intellectual Property Ethics | -against | secondary | -0.50 |
| Overall incident score = | -0.241 | ||
Score = avg(topic contributions) × significance (medium ×1) × confidence (0.64)× agency (negligent ×0.5)
Evidence (2 signals)
VentureBeat: Cursor's Composer 2 was secretly built on a Chinese AI model
VentureBeat coverage of the disclosure gap and the broader licensing/attribution dispute with Moonshot AI over Kimi K2.5's terms.
TechCrunch: Cursor admits its new coding model was built on top of Moonshot AI's Kimi
Cursor VP Lee Robinson and co-founder Aman Sanger confirmed Composer 2 started from Moonshot AI's open-weight Kimi K2.5 base after a developer identified the model fingerprint, with Sanger calling the lack of disclosure in the launch blog post 'a miss.'