Open Letter on Transparent AI Cyber Protections

Dear Secretary Lutnick and National Cyber Director Cairncross,

We, the undersigned executives and technical leaders from across the United States and its allies, write to you to ask you to lift the export control directives on Anthropic’s Fable and Mythos large language models and commit to an open, scientific and transparent process of handling AI risk assessments in the future.

First, we would like to state that we believe that:

AI is having significant impacts on cybersecurity , including by greatly reducing the difficulty of finding flaws in software and writing exploits for those flaws.

Anthropic’s Mythos-class models are quite good at finding flaws and weaponizing exploits .

However, they are not uniquely good at these tasks, and many of the undersigned individuals regularly use other foundation and open-source models for security audits and red-teaming every day.

Anthropic has built multiple protections into the Fable model to prevent its use for cyber offensive uses. These protections were so aggressive as to be the source of humor in the cyber community on launch day.

It is essential to provide AI to coders and security teams so they can find and fix flaws in their own newly-written as well as decades of legacy code faster than our adversaries.

The Chinese open-weight models are only months behind the best American models, and those are the models we know about . It seems likely that the PRC government has access to private capabilities beyond what has been published.

To pull the best capabilities away from defenders without a good reason when our adversaries are rapidly advancing is dangerous .

It is our understanding that underlying model capabilities in the original research that triggered this action:

Were focused on determining whether a human-prompted section of code was insecure . This is a necessary capability in any model that is intended to write secure code and should not be considered an offensive capability.

Can be replicated on GPT-5.5, Opus, Sonnet and even Chinese models like Kimi 2.7 . The justification for this unprecedented action was that Fable provides a unique “uplift” of capabilities beyond other AI models, but AI has been finding bugs and generating working exploits at superhuman levels since last year.

Anthropic is addressing the research. As security professionals, we recognize that our work does not lead to a simple end-state where a system is fully safe, and the purpose of research like this is to enable continuous improvement, not to ban the technology.

As a result, this action has taken the best models away from defenders, created market uncertainty, and risked America’s AI leadership without any real risk to justify it.

Not all of us agree that AI regulation is the right way forward. But if this Administration’s laudable goal of securing our nation’s critical infrastructure is going to include models being regulated, then the regulations should be:

Grounded in scientific evaluations developed with input from industry and academia;

Created through a democratic rule-making process;

Enforced transparently and fairly with appropriate time given to remediate; and

Used only to the minimal extent necessary to ensure the safety of the American public.

Thank you for your consideration and partnership in helping us maintain America’s lead in technology while protecting critical software and systems.

Signed,

Affiliations are included for reference only and do not indicate organizational endorsement.

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Alex StamosChief Product Officer, Corridor

Derek AbdineCEO, Furl

Feross AboukhadijehCEO, Socket

Ben AdidaExecutive Director, VotingWorks

Iftach Ian AmitFormer CSO, Founder and CEO at Gomboc.ai

Omkhar Arasaratnam

Matthew ArenoCTO

Abhishek AryaPrincipal Engineer, Google and Founder, OSS-Fuzz

James Nicholas AshworthAI Village

Emily AustinPrincipal Security Researcher

Megan BakerCISO, Georgian

Kevin BankstonSenior AI Governance Advisor, Center for Democracy & Technology

Kurt BaumgartnerCo-Founder, TLPBLACK

Andrew BechererCISO, Socket

Brian BehlendorfOpen Source Pioneer

Anthony BettiniCEO, VulnCheck

Manish Bhatt0-day Connoisseur, OWASP

Matt BishopDistinguished Professor, University of California Davis

Christopher Bleckmann-DreherPrincipal Offensive Security, Mercedes-Benz

JP BourgetCEO, Blue Cycle

Aaron BrownHead of Security, Mercor

Jack CableCEO & Co-founder, Corridor

Jon CallasIndiana University

Justin CalmusCISO

Jeffrey CarusoAuthor and Researcher

Sven CattellAI Village

Jason ChanRetired CISO

Anupam ChanderProfessor of Law and Technology, Georgetown

Matthew CreagerCo-Founder, Keycard

Andrew CunjeCISO, Appian

Dino A. Dai Zovi

J. Michael DanielPresident & CEO, Cyber Threat Alliance

Sam Davison

Drew DennisonCTO & Co-Founder

Justin DollyChief...