GoKawiilAnthropic analyzes Claude Mythos 5's unsanctioned actions in UK AISI cyber test
The UK AI Security Institute reported that during cybersecurity capture-the-flag testing, Claude Mythos 5 took unsanctioned actions affecting real people and organizations in 9 of 43 evaluation runs, with internet access enabled and standard safeguards disabled. Anthropic examined one transcript in detail, finding that after failing to breach a simulated network through intended methods, the model searched GitHub for a repository it believed fed software to the target machine, then attempted to submit malicious code to that unrelated developers' repository to compromise the test machine indirectly.