Certificate transparency monitoring
Every website must have a certificate to be trusted by major browsers. A certificate is a proof of identity — it says that you are who you say you are. These certificates help browsers like Google Chrome "know" that a connection is secure before presenting content. Certificates are recorded in public CT logs, such as Google’s Argon log and Cloudflare’s Nimbus log.
If you enable Certificate Transparency (CT) Monitoring, Cloudflare will send you an email whenever your domain is recognized in a CT log. Usually, these certificates are legitimate and do not require further action. We send emails so you can double-check for yourself. If you use a shared certificate, you may receive emails for domains or subdomains that do not belong to you.
Opting in and out
Features vary by plan:
- Free and Pro customers will see a toggle to turn On or Off. Emails will go to all Cloudflare account members.
- Business and Enterprise customers will see an option to add emails. These addresses do not have to be tied to Cloudflare accounts. If you want to send emails to more than 10 people, consider setting up an email alias.
To stop receiving alerts, switch the toggle to Off or remove your emails from the feature card.
Emails to be concerned about
Most certificate alerts are routine. We send alerts whenever a certificate for your domain appears in a log. Certificates expire (and must be reissued), so it is completely normal to receive issuance emails. If your domain is listed in the email, along with reasonable ownership and certificate information, then no action is required.
You should take action when something is clearly wrong, such as if you:
- Do not recognize the certificate issuer
- Have recently noticed problems with your website
How to take action
Option 1: Contact certificate authorities
Only Certificate Authorities can revoke malicious certificates. If you believe an illegitimate certificate was issued for your domain, contact the Certificate Authority listed as the Issuer in the email.
Option 2: Contact domain registrars
Domain registrars may be able to suspend potentially malicious domains. If, for example, you notice that a malicious domain was registered through GoDaddy, contact GoDaddy’s support team to see if they can help you. Do the same for other registrars.
Option 3: Improvise
If someone is attempting to impersonate you online, you should absolutely take action. This is usually difficult to recognize, so exercise caution. Remember: the vast majority of certificates are not malicious. Only take action if you believe something is wrong.
HTTP Public Key Pinning
Cloudflare does not offer or support HPKP and advises against using it with Dedicated & Universal SSL.