Upgrading from Istio versions 1.5 and prior, to 1.6 and later, may result in access control bypass

If you’re upgrading from an earlier version to Istio 1.6 or later, the container ports for the Istio gateway will change. You may need to update any custom access control rules to reflect that change.

Please check out our security advisory: Istio / ISTIO-SECURITY-2021-002