Steps to Reproduce
To determine whether an instance is affected:
Navigate to System Definition > Plugins and activate the Service Portal plugin.
Open a browser window to a Service Portal (for example, /sp).
If the browser throws a 404 error failing to download /sp-fonts/glyphicons-halflings-regular.woff2, the instance is affected.
Create a system property (sys_properties) record as follows:
Value: pa,html,script,include scripts,glide,custprefix,_sn
This new system property is provided in the High Security plugin for new Helsinki instances with this default value, but it is not provided for upgrading instances.
Related Problem: PRB713048