Breaches and incidentsBriefConfirmed by two or more outlets
Mythos Preview unauthorized access through a third-party vendor environment
Bloomberg, about 21 Apr 2026: a private Discord group had used Mythos since roughly 7 Apr, through a contractor’s still-valid credentials and guessing of...
- Disclosed
What happened
- Bloomberg, about 21 Apr 2026: a private Discord group had used Mythos since roughly 7 Apr, through a contractor’s still-valid credentials and guessing of model endpoints (reportedly the Mercor vendor environment). Anthropic is investigating and says there is no impact on its own systems.
- Developer lesson: offboard vendor and contractor credentials.
Sources
- https://fortune.com/2026/04/24/technology-anthropic-mythos-discord-breach-ai-cybersecurity-vulnerability-patch-window/
- https://www.techbrew.com/stories/2026/04/23/random-discord-group-got-anthropic-mythos-before-cisa
- https://www.heise.de/-11266912
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