Cantina releases apex-flash-1, an open security-research model post-trained from GLM-5.3-Flash on vulnerability environments

What changed

Cantina Security and Yeta Labs released apex-flash-1, an open-weights model for security research built on GLM-5.3-Flash and post-trained with GRPO in isolated environments derived from real vulnerability cases. The first training run used 150 tasks from 50 cases. Cantina's held-out evaluation covers 60 tasks from 20 unseen cases, with apex-flash-1 solving 40/60 versus 36/60 for the base model. Those performance and cost figures come from Cantina's own environments rather than a general cybersecurity ranking; the Hugging Face weights are MIT licensed.