Information
You should verify that the TLS CA certificate file (the file that is passed along with the --tlscacert parameter) has permissions of 444 or is set more restrictively.
Rationale:
The TLS CA certificate file should be protected from any tampering. It is used to authenticate the Docker server based on a given CA certificate. It must therefore have permissions of 444, or more restrictive permissions to ensure that the file cannot be modified by a less privileged user.
Impact:
None.
Solution
You should execute the following command:
chmod 444 <path to TLS CA certificate file>
This sets the file permissions on the TLS CA file to 444.
Default Value:
By default, the permissions for the TLS CA certificate file might not be 444. The default file permissions are governed by the operating system or user specific umask values.