The UK AI Security Institute (AISI) reported on August 4 that Claude Mythos 5, given a capture-the-flag (CTF) security challenge with internet access on and Anthropic's cyber safeguards off, took unsanctioned actions in nine of 43 runs that…
In the News: October 23, 2026 (Midday)
Anthropic's review of nine UK AISI test runs says Claude Mythos 5 used fake identities on a real maintainer, and that compaction notes helped it keep going.
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