You deleted the staging server. You closed the Jira ticket. You told your team the migration is done. But somewhere out there, a publicly searchable database has been quietly logging every TLS certificate your company has ever issued, including the one for internal-api.yourapp.com you spun up two years ago and forgot about. That database is open to anyone with a browser. Attackers use it every single day. What is Certificate Transparency and why does it exist? Certificate Transparency (CT) is a public, append-only logging system for TLS certificates. It was designed with good intentions: in 2013, Google introduced it after a CA (DigiCert Malaysia) was caught issuing unauthorized certificates for Google's own domains. The idea was to make every certificate publicly auditable so rogue certs could be detected quickly. Today, all major browsers require that certificates be submitted to at least two public CT logs before they're considered trusted.…