Anthropic Crackdown Alarms 150 Cyber Leaders
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- Alex Stamos, former Facebook security chief, organized an open letter signed by nearly 150 security leaders calling on the Trump administration to reverse restrictions on Anthropic's Fable 5 and Mythos 5, saying it sets a precedent that 'American models can't do defensive security research.'
- Amazon CEO Andy Jassy's reported call flagging security concerns about Anthropic's models — alongside fears of Chinese access to Mythos — triggered the administration's restriction push after Anthropic publicly released its first Mythos-class model.
- Anthropic brought in a leading zero-day bug hunter who helped the Defense Department create its bug-bounty program to help assess Amazon's concerns; the White House is now casting that researcher as a 'radical Democrat.'
- Stamos, who spoke with technical staff involved in the fallout, said Amazon's flagged findings do not appear unique to Anthropic's models and instead center on a jailbreak allowing Fable to write 'proofs of concept' — a capability defenders use to understand and fix vulnerabilities.
- Luta Security CEO Katie Moussouris, who reviewed Amazon's findings, concluded the issue involved prompts supporting defensive security work, not mass exploitation, and warned any fix would render the model less useful for cyber defenders.
- Cyber experts warn that if frontier AI companies fear punishment for vulnerability-identifying capabilities, they may strip them out — while Chinese AI developers and government-backed hacking groups are unlikely to follow suit, potentially giving adversaries an advantage.
- The White House is standing up a vulnerability clearinghouse under a recent AI security executive order, but questions linger about remaining cyber talent after recent senior cyber-policy departures and the sidelining of CISA.
Why it matters: By penalizing one of the few U.S. AI companies actively building defensive security tools, the administration may push every frontier lab to remove vulnerability-finding capabilities their own defenders rely on — handing Chinese state-backed hackers capabilities American teams can no longer access. The timing matters: this fight comes as CISA faces staff departures and the White House has lost multiple senior cyber-policy officials, leaving fewer hands to triage the very threats the new executive order aims to catalog.
