UnForm on Windows includes the Apache httpd web server. If you wish to update this to a current version, you can do so manually by simply replacing the contents of the UnForm server's httpd folder with a download from the Apache organization's recommended vendor, ApacheLounge.
As shown in the Apache organizations download page (https://httpd.apache.org/download.cgi), you can download the latest Apache Windows binary from here:
https://www.apachelounge.com/download/
The latest version will be a 2.4.xx link near the top of the page. This will download a zip file. In the zip file will be an "Apache24" folder. In this folder will be a series of folders, such as bin, lib, and modules. The entire contents of the Apache24 folder can be extracted to the "httpd" folder under the UnForm installation path, which itself will contain the same files and folders. Replace them all with those in the zip file's Apache24 folder and restart UnForm.
If you are unsure where the UnForm server is installed, you can look at the UnForm service's properties. It will indicate a "Path to executable" that is a file in the "rt" folder under where UnForm is installed.
The latest 2.4.xx version of Apache will be compatible with both UnForm 10.0 and 10.1.