[Bug]: CN not added as SAN

[GBBx]

Steps to Reproduce

1. Create CSR without specifying SAN:

openssl req \
  -new -newkey rsa:4096 \
  -out example.com.csr \
  -keyout example.com.pem \
  -subj "/C=AU/ST=Example/L=Example/O=Example Ltd./OU=Example Team/CN=example.com.crt"

2. Sign certificate:

step certificate sign \
  example.com.csr \
  /etc/step-ca/certs/root_ca.crt \
  /etc/step-ca/secrets/root_ca_key > example.com.crt

3. Check SAN of certificate:

openssl x509 -noout -ext subjectAltName -in example.com.crt
No extensions in certificate

Your Environment

• OS - Ubuntu 22.04
• step-ca Version -

Smallstep CLI/0.25.1 (linux/amd64)
Release Date: 2023-11-29T03:45:04Z

Expected Behavior

The common name should be automatically added as a SAN.

Actual Behavior

The SAN is empty.

Additional Context

No response

Contributing

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