On May 18, 2026, Project Glasswing: what Mythos showed us 2026-05-18 Grant Bourzikas 9 min read This post is also available in 简体中文 , 한국어 , Español and 繁體中文 . For the last few months, we've been testing a range of security-focused LLMs on our own infrastructure.
What the source shows
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. Model refusals in legitimate vulnerability research The Mythos Preview model provided by Anthropic, as part of Project Glasswing, did not have the additional safeguards that are present in generally available models (like Opus 4.7 or GPT-5.5). 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 .
Why it matters
What changed with Mythos Preview Mythos Preview is a real step forward, and it's worth saying that plainly before getting into anything else. We've been running models against our code for a while now, and the jump from what was possible with previous general-purpose frontier models to what Mythos Preview does today is not just a refinement of what came before. So rather than trying to benchmark Mythos Preview against general-purpose frontier models, it's more useful to describe what it can actually do, and two features that stood out across the work we did with Mythos Preview: Exploit chain construction - A real attack rarely uses one bug. Proof generation - Finding a bug and proving it's exploitable are two different things, and Mythos Preview can do both.
Key Questions
Q: What happened or was found?
A: On May 18, 2026, Project Glasswing: what Mythos showed us 2026-05-18 Grant Bourzikas 9 min read This post is also available in 简体中文 , 한국어 , Español and 繁體中文 . For the last few months, we've been testing a range of security-focused LLMs on our own infrastructure.
Q: What concrete evidence or constraint does the source provide?
A: Project Glasswing: what Mythos showed us 2026-05-18 Grant Bourzikas 9 min read This post is also available in 简体中文 , 한국어 , Español and 繁體中文 .
Source: Project Glasswing: what Mythos showed us
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