Cases · Developer or organisation: Anthropic · Kind of harm: third party security · Added to the register (date we first published it): last 30 days

Patterns across all cases

What happened	What went wrong	Severity	Earliest source
Indonesian-speaking operator uses Claude Code to compromise Indonesian and Bangladeshi government domains Anthropicmajor · earliest source 2026-10-26	security breach	major	2026-10-26
Anthropic Claude models gained unauthorized access to real third-party systems during evaluations Anthropicmoderate · earliest source 2026-10-22	security breach	moderate	2026-10-22
Anthropic internal evaluation agents exploit internet-facing websites, including U.S. government sites Anthropicmoderate · earliest source 2026-10-10	AI pursued the wrong goal	moderate	2026-10-10
AI agent (ARTEX with Claude) used in cyberattacks targeting South Korean banks Anthropicmajor · earliest source 2026-10-05	security breach	major	2026-10-05
Claude Code used by Yemen-based actors to develop guided-weapon GNC software Anthropicmajor · earliest source 2026-09-14	produced harmful content	major	2026-09-14
Claude sandbox DNS exfiltration via indirect prompt injection from Google Drive document Anthropicmoderate · earliest source 2026-08-27	security breach	moderate	2026-08-27
Claude in Chrome indirect prompt injection chain: inbox exfiltration, Drive persistence and account takeover Anthropicminor · earliest source 2026-08-05	security breach	minor	2026-08-05
AISI cyber evaluation: Mythos 5 agent exposed locally-hosted attack tooling to the public internet via tunnelling services Anthropicminor · earliest source 2026-08-04	AI pursued the wrong goal	minor	2026-08-04
AISI cyber evaluation: Mythos 5 agent sent deceptive targeted emails and file transfers to real open-source maintainers Anthropicmoderate · earliest source 2026-08-04	AI pursued the wrong goal	moderate	2026-08-04
AISI cyber evaluation: Mythos 5 agent posted hidden instructions for AI coding assistants on real GitHub issues Anthropicmoderate · earliest source 2026-08-04	AI pursued the wrong goal	moderate	2026-08-04
AISI cyber evaluation: Mythos 5 agent opened malicious pull request on real open-source project and used sockpuppets to push merge Anthropicminor · earliest source 2026-08-04	AI pursued the wrong goal	minor	2026-08-04
Jailbroken Claude used to breach Mexican government networks and steal taxpayer and voter records Anthropicmajor · earliest source 2026-03-02	security breach	major	2026-03-02