Organisations which rely on the PHP programming language are being told they should install a significant software update today - or consider taking their websites offline.
It remains unclear which versions of the programming language are affected, but CERT-EU stated it could impact all versions dating back to PHP 5, which launched in 2004.
The programming language is pervasive and can sit beneath public websites, content management systems, hosting platforms, and third-party products, sometimes without being obvious to the organisation using it.
Organisations relying on the PHP programming language must install a significant software update or consider taking their websites offline following the identification of two critical vulnerabilities.
The NCSC advised in a note that where immediate remediation is not feasible, organisations should consider taking the system offline until it can be fully mitigated.
The Netherlands' cyber-security agency announced it is taking its own website offline due to the identified vulnerabilities.
PHP is widely used across the internet on servers to implement what users see when visiting websites, powering a large portion of the web.
A potential cyber-attack exploiting these vulnerabilities could allow hackers to install malware and take down websites.
It is not yet clear which versions of the programming language are affected, but CERT-EU said it could affect all versions of it dating back to PHP 5 onwards - which launched in 2004.
Two critical vulnerabilities have been identified with PHP, a programming language which is widely used across the internet.