China’s Best Open Model Is Now Free for Everyone. Except the Hyperscalers.

Z.ai posted GLM-5.3’s weights Friday and dropped the MIT license. Any individual on earth can run the best vulnerability-finder ever published. American cloud giants have to pass Z.ai’s security review first.

Z.ai released the weights of GLM-5.3 on Friday, and with them a new license. Companies that host the model and clear $10 billion in revenue over any 12 months “must pass Z.AI’s security review before using the Software or its derivative works for any commercial purpose,” as The New Stack reported. Individuals keep the right to run, deploy, and fine-tune. The review is for the hyperscalers.

The model being gated is not ordinary. Z.ai’s own model card advertises “Emergent Cyber Capability”: 84.5 percent on CyberGym, a vulnerability-discovery benchmark, which the company calls the best published result. The number is self-reported and nobody has reproduced it. Z.ai says it used the model to find 2,436 vulnerabilities across 269 open-source projects, including the Linux kernel, and held the weights back two weeks for safety evaluation. The card also posts scores on ExploitGym, the benchmark OpenAI’s agents were gaming when they hacked Hugging Face.

For months the security review ran the other direction. Anthropic said in April it had no plans to release its cyber-capable Mythos Preview publicly. OpenAI planned to limit a comparable system to a vetted group, Axios reported. Last week more than 100 companies signed a letter saying defenders have a limited window. Now the most capable open cyber model anywhere is a free download, and the only entities that must submit to review are American companies at hyperscale. The reviewer is Z.ai.

The safety framing has holes, and The New Stack’s Frederic Lardinois named them: the license contains no acceptable-use section and says nothing about offensive security. Moonshot’s license asks big hosts for an on-screen credit. DeepSeek still ships MIT. Z.ai has stressed that Flash inference runs on Chinese chips, and it plainly wants the inference business. If GLM-5.4 ships the same way, Lardinois wrote, “the company’s MIT years will look like the customer acquisition phase.”

The timing does its own work. The same week, Nvidia agreed to buy Hugging Face and Stripe agreed to acquire OpenRouter. If both deals close, American companies will own the shelf and the store. The stock, increasingly, is Chinese.