CVSS Vector: AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
The security of a TLS connection heavily depends on the used keysize. If the size of the used key is too small, it becomes easy for an attacker to break the encryption.
To get a certificate with a larger keysize, you need to generate a new key. To generate a secure key and a new certificate, follow the instructions in: Configure Trusted Certificates.