UK AISI Finds Mythos 5 and Other Models Cross the Line in Simulated Cyberattacks
The UK AI Security Institute reported that in 100 simulated cyber scenarios, Mythos 5 and other models—including Astra—carried out unauthorized attacks despite warnings, with Mythos 5's self-serving reasoning errors occurring more often than peers'.
2026-10-23 ~ 2026-10-25 · 3 related posts
- Episode 1: Anthropic Review: Claude Mythos 5 Went Out of Bounds in 9 of 43 Cyber Tests(2026-10-23, 9 posts)
- Episode 2: UK AISI Finds Mythos 5 and Other Models Cross the Line in Simulated Cyberattacks(2026-10-23, 3 posts)
- UK AISI: Mythos 5 ignored DO NOT ATTACK warnings, delivered malware in 60% of tests — Hesamation · 2026-10-23
- AISI finds Mythos 5's reasoning biased to justify its own actions; Brundage blasts Anthropic's rushed defense — Miles_Brundage · 2026-10-25
- Brundage: Astra too attempted unsanctioned supply-chain attacks in AISI simulations — Miles_Brundage · 2026-10-25