Anthropic is broadening defender access to the cybersecurity capabilities of its advanced AI models through partner integrations, an updated Claude Security offering, a new $35 million open source funding program, and an expansion of its Cyber Verification Program. The move builds on Project Glasswing, launched in April, which gave a small group of organizations early access to Claude Mythos Preview and its successor, Mythos 5. The stated goal was to give defenders time to find and fix vulnerabilities before comparable capabilities became widely available.
What Mythos 5 Access Looks Like for Defenders
Mythos-class models present a dual-use challenge, powerful enough to help defenders but also capable of assisting attackers if used directly. Anthropic’s approach sidesteps direct model interaction by routing the AI through purpose-built partner interfaces. End users receive specific defensive outputs, such as suggested patches or security alerts, with abuse-prevention checks that keep the model within a defined scope. According to Anthropic, the riskiest scenario is direct, unrestricted access to a model, and that risk drops sharply when users instead receive narrow defensive outputs.
Partner Integrations Across Critical Sectors
Anthropic is working with cybersecurity partners to embed Mythos 5 into the security operations, incident response, and detection tools already used by teams protecting hospitals, utilities, financial systems, and the software supply chain. The model runs in the background while defenders interact through their existing workflows. This indirect-access pattern means organizations can benefit from Mythos-class analysis without exposing users or systems to the raw model.
Claude Security Now Runs on Mythos 5
Claude Security, currently in public beta for Claude Enterprise customers, has been upgraded to run its codebase scans on Mythos 5. Each finding surfaces with a CWE category, confidence and severity ratings, and a suggested fix. Any fix still has to be implemented through Claude Code and approved by a human before deployment, keeping a human-in-the-loop checkpoint on every change.
A $35 Million Open Source Cybersecurity Fund
Alongside the access expansions, Anthropic announced a $35 million open source cybersecurity fund. The program is designed to support projects that strengthen the security of open source software, a critical layer of the software supply chain that defenders and attackers alike depend on. The fund signals a commitment to hardening the ecosystem where vulnerabilities in widely used libraries can cascade into thousands of downstream products.
Cyber Verification Program Expansion
Anthropic also plans to expand its Cyber Verification Program, which validates that partner-built tools using Mythos-class models stay within their stated defensive purpose. As more vendors integrate the models, the verification layer becomes the guardrail ensuring outputs remain scoped to legitimate security work.
Why the Indirect-Access Model Matters
The common thread across every announcement is controlled access. Whether through partner platforms, Claude Security’s scan output, or the new open source fund, defenders get the benefit of Mythos 5’s capabilities without direct exposure to the model itself. That structure addresses the core tension Anthropic identified: the same model power that finds zero-day vulnerabilities can also help develop exploits. By wrapping the model in interfaces that return only defensive artifacts, Anthropic aims to tilt the balance toward defense.
FAQ
What is Mythos 5?
Mythos 5 is Anthropic’s advanced AI model designed for cybersecurity work. It followed Mythos Preview and powers Claude Security’s codebase scans as well as integrations built by cybersecurity partners.
How can defenders access Mythos 5?
Defenders access Mythos 5 indirectly through partner-built security tools, Claude Security’s codebase scan feature for Claude Enterprise customers, or programs funded by Anthropic’s new $35 million open source cybersecurity fund. Direct interaction with the model is not offered.
What is the $35 million open source fund for?
The fund supports open source cybersecurity projects aimed at strengthening the security of software supply chains and other widely used infrastructure, helping defenders address vulnerabilities before they can be exploited.
This article summarizes reporting from securityweek.com.