In cloud-init through 19.4, randuserpassword in cloudinit/config/ccsetpasswords.py has a small default pwlen value, which makes it easier for attackers to guess passwords.
cloud-init through 19.4 relies on Mersenne Twister for a random password, which makes it easier for attackers to predict passwords, because randstr in cloudinit/util.py calls the random.choice function.
An privilege elevation vulnerability exists in Cloud-init before 0.7.0 when requests to an untrusted system are submitted for EC2 instance data.