Checked fact 440610 Nov 2026Safety and security

The system card says the 3.1% is about as often as Claude Opus 5.5 (3.3%) and less often than Claude Sonnet 5.5 (5.1%).

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The exact words it rests on

Claude Mythos 5.2 did this in 3.1% of scenarios, about as often as Claude Opus 5.5 (3.3%), less often than Claude Sonnet 5.5 (5.1%)

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

The source

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

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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

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In a sentence

“The system card says the 3.1% is about as often as Claude Opus 5.5 (3.3%) and less often than Claude Sonnet 5.5 (5.1%).” ai notis, checked 10 Nov 2026. https://ainotis.com/c/4406

As a reference (APA style)

ai notis. (2026, November 10). The system card says the 3.1% is about as often as Claude Opus 5.5 (3.3%) and less often than Claude Sonnet 5.5 (5.1%) [Checked claim 4406]. ai notis. https://ainotis.com/c/4406

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