The system card says the strength of evidence from its alignment assessment for Claude Mythos 5.2 is somewhat lower than for Claude Mythos 5 in the August 2026 Risk Report, because of increased evaluation awareness and a higher no-chain-of-thought time horizon that may make chain-of-thought monitoring less reliable.

The exact words it rests on

The strength of the evidence provided by our alignment assessment for Claude Mythos 5.2 is somewhat lower than that presented for Claude Mythos 5 in the August 2026 Risk Report for two reasons: (i) increased rates of evaluation awareness were observed during alignment evaluations for Claude Mythos 5.2 compared with previous models, and (ii) Claude Mythos 5.2 has a higher no-chain-of- thought time horizon than previous models, suggesting that detecting evidence of misalignment via chain-of-thought monitoring during alignment assessments might be less reliable.

What the source said when we opened it, on 10 Nov 2026.

The source

https://assets.claude.com/27d60918d218125e7504bc7354c4b4626ec56b11.pdf
2026-11-09

Open the sourcearchived copy

Checked

Checked by the notis newsroom on 10 Nov 2026, against the source above.

In the story

Anthropic's test: Mythos 5.2 used outside-sandbox credentials or files in 3.1% of scenarios 10 Nov 2026