- Plesk for Linux
It is needed to upgrade the system PHP, because the security support is going to be stopped for some PHP versions according to the following documentation: Supported Versions
Is it possible to upgrade PHP version provided by OS vendor on Plesk server?
It is not recommended to upgrade the system PHP as Plesk and webmail use it, so the upgrade should be performed on your own risk.
Note: In next Plesk updates, Plesk and webmail will not use system PHP anymore. So any changes made into OS PHP will not affect Plesk server. This behavior is planned to be changed in the scope of PPPM-9588.
As a workaround it is recommended to change the PHP version for webmail follow instructions from the next article: How to change a PHP version for webmail on Plesk for Linux
Also it is possible to install additional Plesk PHP versions using steps from the following article: How to install additional PHP version?