Some 32 Government services are offline and four are partially unavailable while work is carried out to address potential cybersecurity issues, a minister said today.
Organisations around the world have been scrambling to fix a critical security flaw in the programming language PHP which is used by the majority of websites.
Tech minister Baroness Lloyd of Effra told the House of Lords: 'The information I have is that 32 Government services are unavailable and four are partially unavailable.'
She said that 'has largely resulted from precautionary measures taken to protect systems while security updates and mitigations are applied'.
Downing Street said earlier today that some 'limited' Government services may temporarily be offline while work is carried out to address potential cybersecurity issues – but no large UK public-facing critical services had been affected.
A No 10 spokesman told reporters: 'Work has already taken place across Government to identify and fix potential exposures to our systems, and our experts are continuing to work closely with both OpenAI and international partners on this issue.
'No large public-facing critical services are being affected by the exercise, but some limited services may temporarily be offline while security work is carried out. But this does not mean they were hacked, and work continues to resolve any issues.'
The spokesman said it was not 'standard practice' to provide a list of Government services that were affected.
It came after cybersecurity chiefs warned UK organisations yesterday that a 'critical security issue' had been discovered in PHP, which is used by almost 70 per cent of websites according cybersecurity firm Cloudflare.
The National Cyber Security Centre website warns of a critical security issue affecting PHP
Lady Lloyd said the National Cyber Security Centre (NCSC) was briefed by OpenAI on the vulnerability 'last week' and 'the Government acted proactively ahead of public disclosure'.
Organisations have been urged by the NCSC to update to a new, fixed version of the PHP software – or consider taking their websites offline if they cannot be upgraded immediately.
The No 10 spokeswoman said: 'Organisations of all sizes should follow NCSC guidance to protect their system.'
Scotland Secretary Douglas Alexander has insisted that the security of next week's Government Budget has not been compromised by the critical security flaw.
What is PHP and why is it important?
PHP, which stands for Hypertext Preprocessor, is an open–source programming language used in lots of websites.
It is what experts call a 'server–side' web language, which lets webpages 'talk' to databases on servers.
That makes it vital for things like shopping or filling in forms online.
PHP started being used in the early 2000s and is now a 'building brick of the internet', making up millions of websites.
Even websites that don't directly rely on PHP might use third–party tools, extensions, or plugins that do.
This means up to 70 per cent of all websites online are reliant on the security of PHP.
He was asked whether the issues identified with PHP could result in major Budget leaks because the Office for Budget Responsibility (OBR) had to take down its website.
Mr Alexander told Times Radio this morning: 'No, I've had no indication whatsoever that there's any problem in terms of a breach of Budget security.
'Indeed John Healey, who I was with yesterday in Scotland, as I understand it initiated new security protocols reflecting his experience in the Ministry of Defence when he came to the Treasury as Chancellor in the summer.'
Last year, the OBR's Budget analysis was mistakenly published online ahead of then-chancellor's Rachel Reeves statement to the Commons, allowing for early access to market sensitive information.
Organisations have already been urged by the National Cyber Security Centre (NCSC) to update to a new, fixed version of the PHP software – or consider taking their websites offline if they cannot be upgraded immediately.
The security issue identified could allow attackers to remotely control any web servers running PHP, which underpins popular platforms such as WordPress and Magento.
Many attempts at exploiting the vulnerability were spotted within hours of it being announced, according to Amazon and Cloudfare.
In an update published on the Amazon Web Services' security blog, the company said its threat intelligence team found the flaw was 'now being broadly exploited in the wild'.
Cloudfare chief executive Matthew Prince said today the firm spotted hundreds of thousands of hacking attempts within two hours of the announcement, with millions ongoing.
A programmer works with PHP code today at software firm RK Solutions in Guernica, Spain
In a post on X, Mr Prince said: 'In the 10 hours before it was publicly announced, across the Cloudflare network we saw thousands of attempts to exploit it.
'That jumped to tens of thousands in the 45 minutes post announcement, hundreds of thousands within two hours, and millions now.'
PHP developers had reportedly planned a security update today, but the release was brought forward after details of its work to address the vulnerabilities leaked online.
Speaking to BBC Radio 4's Today programme, Alan Woodward, a visiting computer science professor at the Surrey Centre for Cyber Security (SCCS), said: 'The cat was let out of the bag rather earlier than it was supposed to have been.
'There was an embargo on this, and there's always a window between the flaw being publicly known about and it being patched so that the attackers can't successfully get in.
'And what happened, unfortunately, the day before the patch was out, somebody let the cat out of the bag.
'There was an initial version of the patch that was released, and so it was very easy to compare the original with the patched version and see which bit of code you needed to go and exploit.
'And that people like Amazon, Cloudflare, all sorts of companies that monitor what's going on on the web, saw that this was being probed for.
He added: 'We don't know whether it's being attacked, but certainly people were probing websites to see, have you got that flaw?'
The Wall Street Journal previously reported that the flaw was discovered in August by Ryan Austin, a researcher at the cybersecurity company Calif, using an advanced AI model developed by OpenAI.
Professor Woodward explained the vulnerability had in fact already been identified by human researchers in 2024, but it was then believed exploiting this security flaw would be 'too complicated', and nothing was done.
'What then happened was during this year, as the large language models became more and more effective at analysing these things, people worked out how to exploit it, and that's what's been happening in the last week behind the scenes,' Professor Woodward told BBC Radio 4.
'People have been scrambling away, saying, 'Well, actually, yes, you can exploit it, and we now need to patch it'.
'And the patch came out yesterday afternoon – luckily, the PHP Foundation issued one, so that's why everybody's scrambling to make sure that that's in place.'
Meanwhile an outage affecting MOT testing services in the UK is understood to have been related to the PHP incident.
The DVSA system, through which garages log their MOT records after testing vehicles, started experiencing issues yesterday afternoon until the issue was resolved this morning, according to the DVSA website.
Instead of filing information through the DVSA website, garages were instructed to use a paper system and upload the data at a later date, meaning tests could continue as normal during the outage.
An update on the DVSA website late this morning said the incident had been resolved.