Peter Eckersley, may his memory be a blessing

Let's Encrypt: Issue with TLS-ALPN-01 Validation Method

2021.06.08 Certificate Lifetime Incident

Let’s Encrypt – Revoking certain certificates on March 4

Let's Encrypt has just turned on stricter validation requirements

Let's Encrypt releases support for wildcard certificates

Let's Encrypt ACMEv2 and Wildcard Launch Delay

Important: What you need to know about TLS-SNI validation issues

Staging Endpoint for ACME v2

Let's Encrypt Permanently Disables TLS-SNI Challenges After Reported Exploit

20180109 Issue with TLS-SNI-01 and Shared Hosting Infrastructure (Let's Encrypt)

Let's Encrypt OCSP and Issuance Outage Postmortem

Let's Encrypt now supports issuance for Internationalized Domain Names (IDNs)

Let's Encrypt leaked thousands of email addresses, asks to not post lists