Anthropic says Zhipu's open-weight GLM-5.3 nearly matches Claude Mythos Preview at building exploits

The DecoderSeptember 30, 2026en

Zhipu's open-weight model GLM-5.3 writes cyber exploits nearly as well as Claude Mythos Preview, according to Anthropic. Its smaller Flash variant put together a reliable Chrome attack for just $20.40 at Zhipu's API prices. The model's safeguards are easy to strip out, and unlocked versions are already circulating. Anthropic has its own reasons to sound the alarm, but the US agency CAISI backs up the findings. The article Anthropic says Zhipu's open-weight GLM-5.3 nearly matches Claude Mythos Preview at building exploits appeared first on The Decoder .

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