Precautionary takedowns came as officials warned that bad actors could exploit the flaw in the language used by 70% of sites, meaning millions of websites will need to be fixed.
The organisation behind the language issued a patch on Wednesday after researchers testing cyberdefences discovered the flaw. The underlying vulnerabilities found by the researcher were decades old.
Websites around the globe went dark after a serious vulnerability was found in a computer language used to build much of the world wide web.
In the UK, websites belonging to Edinburgh, Bristol and Oxford councils were taken offline.
Alphabet-owned cybersecurity company Wiz said in a blog post that it too had discovered it with the help of Wiz Atlas, its autonomous AI vulnerability research tool, as well as Google’s Gemini 4 Argon and OpenAI’s GPT-5.6 Sol. Cybersecurity company Calif said in a blog post it found the flaws with the help of a large language model on 1 August and had been working on a fix ever since.
Because a fix is now public and AI tools are able to reverse engineer the bug with little effort, experts said they were bracing for a wave of intrusions as hackers jumped to get ahead of the updates. The attempt on the system came from an anonymous internet address, suggesting the activity was conducted by a threat actor, Moses said, adding that it was unclear how the actor learned of the flaws while they were under embargo.