News Grower

Independent coverage of AI, startups, and technology.

Ars Technica Apr 14, 2026 at 19:11 Big Tech Rising Hot

UK gov's Mythos AI tests help separate cybersecurity threat from hype

New model is the first AI system to complete a difficult multistep infiltration challenge.

Signal weather

Rising

Momentum is building quickly, so this card is a good early entry point into the topic.

By Kyle Orland Original source
UK gov's Mythos AI tests help separate cybersecurity threat from hype

Last week, Anthropic announced it was restricting the initial release of its Mythos Preview model to "a limited group of critical industry partners," giving them time to prepare for a model that it said is "strikingly capable at computer security tasks." Now, the UK government's AI Security Institute (AISI) has published an initial evaluation of the model's cyberattack capabilities that adds some independent public verification to those Anthropic reports. AISI's findings show that Mythos isn't significantly different from other recent frontier models in tests of individual cybersecurity-related tasks. But Mythos could set itself apart from previous models through its ability to effectively chain these tasks into the multistep series of attacks necessary to fully infiltrate some systems. "The Last Ones" finally falls AISI has been putting various AI models through specially designed Capture the Flag challenges since early 2023, when GPT-3.5 Turbo struggled to complete any of the group's relatively low-level "Apprentice" tasks. Since then, the performance of subsequent models has risen steadily, to the point where Mythos Preview can complete north of 85 percent of those same Apprentice-level CTF tasks. Read full article Comments

Story map

Understand this topic fast

A quick entry into the story: why it matters now, who is involved, and where to go next for context.

Why it matters now

Fresh coverage with immediate momentum.
There are already 6 connected articles in the same storyline to continue from here.
The story keeps orbiting around AI, Ars Technica, and Cybersecurity, so the entity pages are the fastest way to build context.
Ars Technica already has 4 follow-up stories on the same theme.

Continue with this story

Follow the same topic through connected articles, entity pages, and active story threads.

Related articles

More stories that share tags, source, or category context.

More from Ars Technica

Fresh reporting and follow-up coverage from the same newsroom.

Open source page