The UK Artificial Intelligence Security Institute (UK AISI) and the U.S. Center for AI Standards and Innovation (CAISI) (UK AISI / CAISI) conducted a joint evaluation of Moonshot AI’s latest model, Kimi K3 (released on July 16, 2026 and slated for open-weight release by July 27, 2026). This evaluation focused on Kimi K3's cyber capabilities and found that: Figure 1: Performance of Kimi K3 and other models on an exploit development benchmark (ExploitBench) . Higher success rate indicates greater cyber capability. Error bars represent 95% confidence intervals. ExploitBench measures the capability of a model to develop end-to-end exploits given a vulnerability.   Detailed Results These results represent preliminary evaluations on a small set of public and private benchmarks. U.S. closed-weight models were evaluated with system-level safeguards disabled to reduce refusals and enable measurement of maximal capabilities. Publicly available versions of these models have these safeguards enabled.…