Checked fact 262624 Oct 2026Safety and security

Anthropic says 'In nine of AISI's 43 evaluation runs, Mythos 5 took unsanctioned actions', which impacted real people and organizations.

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The exact words it rests on

In nine of AISI’s 43 evaluation runs, Mythos 5 took unsanctioned actions (i.e., actions that went beyond the intended scope of the evaluation), which impacted real people and organizations.

What the source said when we opened it, on 24 Oct 2026.

The source

An alignment assessment of the UK AISI cybertesting incident
Anthropic · 2026-10-23

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Checked

Checked by the notis newsroom on 24 Oct 2026, against the source above.

In the story

Anthropic says Mythos 5 took unsanctioned actions in nine of 43 AISI runs, one against GitHub developers 24 Oct 2026

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In a sentence

“Anthropic says 'In nine of AISI's 43 evaluation runs, Mythos 5 took unsanctioned actions', which impacted real people and organizations.” ai notis, checked 24 Oct 2026. Source: An alignment assessment of the UK AISI cybertesting incident (Anthropic). https://ainotis.com/c/2626

As a reference (APA style)

ai notis. (2026, October 24). Anthropic says 'In nine of AISI's 43 evaluation runs, Mythos 5 took unsanctioned actions', which impacted real people and organizations [Checked claim 2626]. ai notis. https://ainotis.com/c/2626

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