Anthropic Mythos Preview and AI‑Driven Vulnerability Scanning
Use AI models such as Claude Mythos or GPT‑5.5 to scan your code for vulnerabilities before release.
Use AI scanning tools to proactively find vulnerabilities in your codebase before deployment.
Summary
Anthropic announced the Claude Mythos Preview model in May 2026, a highly capable AI designed to locate software vulnerabilities but restricted to a select group of companies for internal scanning.
The model’s performance rivals that of OpenAI’s GPT‑5.5, which is already publicly available, and smaller, cheaper models from Aisle can reproduce similar results with more prompt engineering.
Mozilla leveraged Mythos to discover 271 previously unknown Firefox vulnerabilities, all of which were patched before release.
The Mythos model is expensive to run and Anthropic has not released it to the general public, citing resource constraints and the potential for misuse.
Both Mythos and GPT‑5.5 demonstrate that AI can accelerate security testing, but they also highlight the risk of attackers using the same technology to find and exploit weaknesses.
Organizations should prepare to integrate AI‑based vulnerability scanners into their development pipelines to stay ahead of potential threats.
Key changes
- Anthropic released Claude Mythos Preview, limited to select companies for vulnerability scanning
- Claude Mythos excels at finding software vulnerabilities but is not publicly released
- OpenAI’s GPT‑5.5, publicly available, matches Mythos in capability
- Aisle reproduced Mythos results with smaller, cheaper models
- Mozilla used Mythos to discover 271 Firefox vulnerabilities that were patched
- Both models enable defenders and attackers to find and exploit software weaknesses