Anthropic: Zhipu’s GLM-5.3 nearly matches Mythos on cyber exploits
On 1 October 2026, Anthropic’s Frontier Red Team reported that GLM-5.3, an open-weight model from Zhipu AI (Z.ai), built end-to-end exploits in 50 of 410 ExploitBench attempts versus 56 for Mythos Preview. Safeguards fall to simple tricks; refusal ablation cost roughly $4,400 in compute.