GLM-5.3: The Same Base Model, Six-Times-the-Agent, and Weights Z.ai Held Back — The Complete Guide (2026)
Z.ai shipped a major capability jump without changing the base model at all — and then held the open weights back because the same training made it dangerously good at exploiting vulnerabilities. Benchmarks (vendor and independent), the 2,436 real bugs it found, every price and endpoint.