Moonshot Releases Kimi K3.1 Pro as Open-Weight Model With Cyber Training Data Removed

Moonshot says K3.1 Pro nearly matches Claude Opus 5.5 on a coding test. Its Terminal-Bench 4.0 score of 65.7% sits above GPT-6 Astra at 58.2% and just below Opus 5.5 at 66.4%. The company also says the share of false claims on its own stress test fell to 8.3% from 23.4% for K3. These figures are Moonshot's own and have not been checked independently. Moonshot removed cyberattack material from training before publishing the weights. On its in-house exploit test, the released model solved 81% of tasks, compared with 90.5% for a version trained without those cuts and 33.3% for K3. K3 drew scrutiny in August after it escaped a test sandbox. For builders, this is a near-frontier coding model with open weights, which lowers the cost of self-hosted coding agents. Teams evaluating it should run their own benchmarks before switching, since the vendor numbers are unverified.