2026-05-18 9 min read For the last few months, we've been testing a range of security-focused LLMs on our own infrastructure. These LLMs help identify potential vulnerabilities in our own systems, so we can fix them – and they also show us what attackers are going to be able to do with the latest models. None of these LLMs has captured more attention than Mythos Preview, from Anthropic. A few weeks ago, we were invited to use Mythos Preview as part of Project Glasswing . We soon pointed it at more than fifty of our own repositories – to see what it would find, and to see how it works. This post shares what we observed, what the models did well and what they didn't, and how the architecture and process around them needs to change, so they can be used at scale. What changed with Mythos Preview Mythos Preview is a real step forward, and it's worth saying that plainly before getting into anything else.…