Government websites across Europe and other regions went offline on Wednesday after security vulnerabilities were found in PHP, a programming language used by millions of websites.
On Tuesday, PHP developers announced nearly two conditions and urged website operators to download updates shortly after finding a solution.
A patched variant was released at around 1:45 p.m. GMT on Wednesday.
Authorities in the Netherlands, Finland and France temporarily shut down public-facing websites as a precaution amid reports that hackers were exploiting the flaws.
The Netherlands took multiple services offline, including government portal Overheid.nl, the Port of Rotterdam website, hospital websites and the websites of major political parties.
Additionally, the country's National Cyber Security Center suspended its public-facing website.
In Finland, state IT provider Valtori temporarily took government public network services offline. France's Interior Ministry also confirmed that local government administrative websites had been taken down while officials awaited a security fix.
Danish municipal IT company Kombit similarly suspended several services, including a national school communication platform.
PHP powers approximately 75% of websites whose programming language can easily be detected, as per technology tracker W3Techs.
It also supports popular platforms such as WordPress, Drupal, Joomla and Magento.
Taking to X (formerly Twitter), Cloudflare Chief Technology Officer Dane Knecht stated the company had detected early attacks and was updating firewall protections as an interim measure.
However, he issued a warning that these measures were not a substitute for installing the security update.
Wordfence, which protects WordPress websites, issued a warning that automatic WordPress updates would not necessarily fix the underlying PHP vulnerabilities.
Cybersecurity agencies in Europe, Australia, Japan and Britain urged users to apply patches immediately or take vulnerable websites offline.
Researchers issued a warning that the widespread use of PHP could expose numerous servers to attacks, particularly smaller websites with limited technical resources.
