UK's top cybersecurity chief warns against AI threats amid Anthropic's new Mythos model

The UK's top cybersecurity official has told Sky News that AI models such as Mythos are "warning shots" for the UK about the danger of powerful AI.

Richard Horne, the head of the National Cybersecurity Centre, stressed the need for organisations to improve their cyber defences, saying they needed to act with "10 times urgency".

But he said he did not consider AI a national security threat at present, as new models were "not finding new attacks, they're just exposing more security vulnerabilities".

He added: "We're in a kind of perfect storm where we have two forces - one huge technology disruption, one rising geopolitical tensions, and they come together. And cybersecurity's in the middle of them."

Anthropic's new model Mythos has been causing widespread concern after the AI firm announced that it was significantly better at finding cyber vulnerabilities than previous AIs.

The company decided not to release Mythos publicly, instead sharing it with a select set of companies and organisations - including the UK AI Security Institute, which independently confirmed their assessment.

Mr Horne said the new abilities of frontier AI models to "do the work of a huge number of people in an instant" made this "a significant moment in time".

He added: "What it's going to mean is where organisations are reliant on technology that they haven't patched, haven't updated with the latest security updates. That will be exposed.

"Where tech producers are shipping code that has this poor quality and has security bugs in it. That will be exposed.

"And where organisations have old, obsolete technology, that can't be updated, it can't be patched. That will be exposed."

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AI, he said, would speed up the need to apply security updates.

"We talked about applying critical patches in days, and that's coming down to minutes," Mr Horne said.

"So, organisations really need to focus on how they execute the application of security updates as quickly as they can."

(c) Sky News 2026: UK's top cybersecurity chief warns against AI threats amid Anthropic's new Mythos model