Comment by SyneRyder

Not a silly question at all. The PHP Foundation page mentions that they were given access to Mythos via a third company, and Anthropic paid for the security audit... and it didn't find this. It somehow took 5.6 Sol, and researchers who knew how to steer Sol.

"Earlier this year, we worked with Alpha-Omega to scan PHP with Anthropic's Claude Mythos. But since the Mythos scan, we have added other tools, including OpenAI's Daybreak Red for validating reports and exploits, alongside sanitizer builds and reproduction environments that match our CI on every platform PHP supports."

https://thephp.foundation/blog/2026/10/21/todays-php-securit...

To me, this is either a black eye for the myth of Mythos, or worse - Mythos deliberately wouldn't reveal this vulnerability to them, even in a Glasswing style approval environment. It might not be the model's own fault, maybe the model was trained by Anthropic not to reveal certain vulnerabilities.

I think Claudes are great, Opus 5.5 has been incredibly helpful at building software and helping in other ways... but I am repeatedly seeing unhelpfulness (more like dismissiveness) from Anthropic models when it comes to cybersecurity defence, and even just secure bugfixes. At least, that's my personal take, on a very grumpy day with very little sleep.