Cross-request KV cache exposure in the GLM-5.3 Workers AI model, and our remediation with SGLang

What happened?

On September 8, 2026, we were alerted by a security researcher, Gadi Evron from Knostic, to a tenant isolation issue affecting the GLM-5.3 Workers AI model ( @cf/zai-org/glm-5.3) starting on August 27, 2026. We have remediated the issue, and we restored the model on September 9. We have confirmed that no other model hosted on Workers AI was affected. Between August 27 and September 9, a small number of customers using the GLM 5.3 Workers AI model received responses that contained data from other customers' requests made to the same model shortly before theirs.