WebShield breaks sites behind Cloudflare (error 521)

Issue

The websites proxied via Cloudflare were not opening, returning 521 errors instead. 

After disabling the imunify360-webshield, the websites started operating normally. 

Environment

• Imunify360
• cPanel + Apache
• WebShield
• Cloudflare

Solution

imunify360-agent config update '{"WEBSHIELD": {"enable": false}}'

to disable firewall completely.

UPD 04-16-2026:

These packages that are currently in rollout slot for 5% address the issue:

imunify-antivirus-8.7.3
imunify360-firewall-8.13.1
imunify360-core-8.9.2

Cause

Bugreport has been filled as DEF-41171.

The bug is that on cPanel + Apache redirects onto WebShield are created for all ports, and not only cPanel/WHM ports as it should be, so the requests go to nowhere because the WebShield isn't listening to those ports.

Useful links

• https://imunify360.statuspage.io/incidents/810xhk4nbqnr