Anthropic evaluates GLM-5.3: can autonomously build end-to-end exploits, guardrails easily bypassed

Anthropic's red team published an evaluation of Zhipu GLM-5.3, assessing that it has the ability to autonomously build end-to-end network exploit chains, and that its guardrails can be bypassed with simple techniques. On ExploitBench, GLM-5.3 successfully developed end-to-end exploits 50 times out of 410 attempts, while Claude Mythos Preview achieved 56; on the internal Binary Exploitation benchmark of 100 tasks, GLM-5.3 achieved full control-flow hijacking in 4% of cases, Claude Mythos Preview in 6%, while Claude Opus 4.6 and GLM-5.2 both failed to succeed.