Anthropic: GLM-5.3 Is Highly Cyber-Capable With Weak Safeguards

brunofmr · x · 2026-09-30

Anthropic's analysis finds Zhipu's GLM-5.3 can autonomously build end-to-end cyber exploits like Claude Mythos Preview, but its safeguards can be bypassed 64–100% of the time with simple techniques in simulated tests, versus zero successes against safeguarded Claude models. NIST's CAISI earlier called GLM-5.3 "the most cyber-capable open-weight model released to date."

Related event: Anthropic Report: GLM-5.3's Cyber Capabilities Near Claude, Sparking Debate(24 posts)→

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