Project Glasswing: Anthropic Shows The AI Train Isn’t Stopping

AlphaAndOmega7 Apr 2026 21:02 UTC
23 points
5 comments4 min readLW link

Note: This was initially written for a more general audience, but does contain information that I feel that even the average LW user might benefit from. Oh, and zero AI involvement in the writing, even if I could have been amused by getting Claude to do the work for me (and even if expect that it would have done a good job at it). If you want a better breakdown of the technical details, read the Model Card or wait for Zvi.

In AI/​ML spaces where I hang around (mostly as a humble lurker), there have been rumors that the recent massive uptick in valid and useful submissions for critical bugfixes might be attributable to a frontier AI company.

I specify “valid” and “useful”, because most OSS projects have been inundated with a tide of low-effort, AI generated submissions. While these particular ones were usually not tagged as AI by the authors, they were accepted and acted-upon, which sets a rather high floor on their quality.

Then, after the recent Claude Code leak, hawk-eyed reviewers noted that Anthropic had internal flags that seemed to prevent AI agents disclosing their involvement (or nature) when making commits. Not a feature exposed to the general public, AFAIK, but reserved for internal use. This was a relatively minor talking point compared to the other juicy tidbits in the code.

Since Anthropic just couldn’t catch a break, an internal website was leaked, which revealed that they were working on their next frontier model, codenamed either Mythos or Capybara (both names were in internal use). This was… less than surprising. Everyone and their dog knows that the labs are working around the clock on new models and training runs. Or at least my pair do. What was worth noting was that Anthropic had, for the last few years, released 3 different tiers of model—Haiku, Sonnet and Opus, in increasing order of size and capability (and cost). But Mythos? It was presented as being plus ultra, too good to simply be considered the next iteration of Opus, or perhaps simply too expensive (Anthropic tried hard to explain that the price was worth it).

But back to the first point: why would a frontier company do this?

Speculation included:

  • A large breakthrough in cyber-security capabilities, particularly in offense (but also in defense) which meant a serious risk of users with access to the models quickly being able to automate the discovery and exploitation of long dormant vulnerabilities, even in legacy code with plenty of human scrutiny.

  • This would represent very bad press, similar to Anthropic’s headache after hackers recently used Claude against the Mexican government. It’s one thing to have your own tooling for vetted users or approved government use, it’s another for every random blackhat to use it in that manner. You cannot release it to the general public yet—the capability jump is large enough that the offensive applications are genuinely concerning before you have defensive infrastructure in place. But the vulnerabilities it’s finding exist right now, in production code running on critical systems worldwide. You cannot un-find them. And you have no particular reason to believe you are the only actor who will eventually find them.

  • Thus, if a company notices that their next model is a game-changer, it might be well worth their time to proactively fix bugs with said model. While the typical OSS maintainer is sick and tired of junk submissions, they’d be far more receptive when actual employees of the larger companies vouch for their AI-assisted or entirely autonomous work (and said companies have probably checked to make sure their claims hold true).

  • And, of course, street cred and goodwill. Something the companies do need, with increasing polarization on AI, including in their juiciest demographic: programmers.

I noted this, but didn’t bother writing it up because, well, they were rumors, and I’ve never claimed to be a professional programmer.

And now I present to you:

Project Glasswing by Anthropic

Today we’re announcing Project Glasswing1, a new initiative that brings together Amazon Web Services, Anthropic, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, NVIDIA, and Palo Alto Networks in an effort to secure the world’s most critical software. We formed Project Glasswing because of capabilities we’ve observed in a new frontier model trained by Anthropic that we believe could reshape cybersecurity. Claude Mythos2 Preview is a general-purpose, unreleased frontier model that reveals a stark fact: AI models have reached a level of coding capability where they can surpass all but the most skilled humans at finding and exploiting software vulnerabilities.

Mythos Preview has already found thousands of high-severity vulnerabilities, including some in every major operating system and web browser.* Given the rate of AI progress, it will not be long before such capabilities proliferate, potentially beyond actors who are committed to deploying them safely. The fallout—for economies, public safety, and national security—could be severe. Project Glasswing is an urgent attempt to put these capabilities to work for defensive purposes.

..

Over the past few weeks, we have used Claude Mythos Preview to identify thousands of zero-day vulnerabilities (that is, flaws that were previously unknown to the software’s developers), many of them critical, in every major operating system and every major web browser, along with a range of other important pieces of software.

Examples given:

Mythos Preview found a 27-year-old vulnerability in OpenBSD—which has a reputation as one of the most security-hardened operating systems in the world and is used to run firewalls and other critical infrastructure. The vulnerability allowed an attacker to remotely crash any machine running the operating system just by connecting to it;

It also discovered a 16-year-old vulnerability in FFmpeg—which is used by innumerable pieces of software to encode and decode video—in a line of code that automated testing tools had hit five million times without ever catching the problem;

The model autonomously found and chained together several vulnerabilities in the Linux kernel—the software that runs most of the world’s servers—to allow an attacker to escalate from ordinary user access to complete control of the machine.

We have reported the above vulnerabilities to the maintainers of the relevant software, and they have all now been patched. For many other vulnerabilities, we are providing a cryptographic hash of the details today (see the Red Team blog), and we will reveal the specifics after a fix is in place.

Well. How about that. I wish the skeptics good luck, someone’s going to be eating their hat very soon, and it’s probably not going to be me. I’ll see you in the queue for the dole. Being right about these things doesn’t really get me out of the lurch either, Cassandra’s foresight brought about no happy endings for anyone involved. I am not that pessimistic about outcomes, in all honesty, but the train shows no signs of stopping.

Edit: A link to the Substack version of this post. I don’t think you should consider me an authoritative source when it comes to AI/​ML, at best I’m the kind of nerd who reads the relevant papers with keen interest. But God knows the quality of discourse around the topic is so bad that you can do worse.

AlphaAndOmega7 Apr 2026 21:02 UTC
23 points
5 comments4 min readLW link