Anthropic Releases Claude Mythos Preview — Locked Behind a 40-Company Firewall
The frontier model scored 73% on expert-level CTF tasks and identified thousands of zero-day vulnerabilities — Anthropic is only sharing it with select partners
Anthropic has confirmed the existence of Claude Mythos Preview, their most capable model to date, while announcing it won't be generally available. Access is restricted to 40 organizations via a new initiative called Project Glasswing.
The Capability Claim
Claude Mythos Preview reportedly represents a "step change" over Claude Opus 4.6 in reasoning and coding. The cybersecurity capabilities, however, are what triggered the restricted release:
- 73% success on expert-level Capture The Flag (CTF) tasks — tasks that no AI model could complete before April 2025
- Multi-stage network attacks executed autonomously in controlled evaluations
- Zero-day discovery — Anthropic used Mythos Preview to identify thousands of zero-day vulnerabilities in major operating systems, web browsers, and common software
- Over 99% of vulnerabilities found are not yet patched
- Exploit generation — reverse-engineering known-but-unpatched vulnerabilities into working exploits
For context: the best previous AI models scored 10-15% on expert CTF tasks. Mythos Preview is roughly 5x better than the previous frontier.
Project Glasswing
Rather than general release, Anthropic created Project Glasswing — a consortium of 40 organizations getting restricted Mythos access. Confirmed members include:
- Microsoft, Apple, Google (OS/platform security)
- CrowdStrike (endpoint security)
- JPMorgan Chase (financial services security)
- Other unnamed defense and critical infrastructure companies
Glasswing members can use Mythos for defensive security work — finding and patching their own vulnerabilities before attackers do. They cannot share model outputs or provide third-party access.
The UK AISI Evaluation
The UK AI Safety Institute (AISI) published an independent evaluation. Their conclusion:
- Capabilities are "genuinely concerning" at current frontier
- Restrictive release was "an appropriate response given capability profile"
- Recommended ongoing monitoring of defensive vs offensive use balance
Why This Matters
For security: The defender-attacker balance shifts. Defenders with Mythos access can find and patch their own vulnerabilities. But once attackers gain equivalent capability (via leaks, open-source competition, or future releases), the attack surface explodes.
For open-source AI: Anthropic is clearly arguing that some capabilities are too dangerous for open weights. Compare with Meta's Llama 4 or DeepSeek V3.2 approach — open weights, let researchers and defenders benefit. The industry divide is widening.
For governance: India, EU, and US regulators are watching. The Council on Foreign Relations published analysis calling Mythos "an inflection point for AI and global security." Expect regulatory pressure.
What Indian Security Companies Should Do
Indian security firms (Tata Consultancy Services, Wipro Cyber Security, HCL Technologies, Zoho Vault, SecurityHQ India) should:
- Apply for Glasswing access if they meet criteria
- Assume attackers will catch up in 6-12 months via open-source competition
- Accelerate patching cadence for critical vulnerabilities
- Invest in AI-native security tooling — the static rule-based era is ending
For standard users: don't panic. This doesn't change your day-to-day security posture immediately. But expect a difficult 12-24 months as the capability gap closes and attackers gain access to similar tools.
Source: red.anthropic.com, Help Net Security, Fortune, Council on Foreign Relations, UK AISI (April 2026)