First identify the type of attack so you can choose the appropriate mitigation strategy. As an easy first step, ask your customers to enable “I’m under attack” mode from your control panel or from their Cloudflare account.
If the attack is directly targeting the root directory of the domain and your integration uses CNAME DNS mode, we suggest signing the customer up with Cloudflare directly and activating Full DNS mode.You can then follow this guide:
You should also contact the Cloudflare support team and provide the domain which is under attack along with detailed attack information, such as logs.
Open a ticket by sending email to firstname.lastname@example.org