Any way to temporarily allow insecure SSL on Safari in High Sierra?
Although there is no longer a button, you can still call CertificateWarningController.visitInsecureWebsiteWithTemporaryBypass() in the Safari Web Developer console to bypass the warning and visit the insecure site.


If not enabled, go to Safari > Preferences > Advanced and select the "Show Develop menu in menu bar" option at the bottom.


Develop > Show Javascript Console.
Paste CertificateWarningController.visitInsecureWebsiteWithTemporaryBypass() in the console.
Press enter to run the code and bypass the warning page without adding the untrusted certificate to your keychain.