When a non-x86 platform is detected, cloud-init grants root access to a hardcoded url with a local IP address. To prevent this, cloud-init default configurations disable platform enumeration.
cloud-init through 25.1.2 includes the systemd socket unit cloud-init-hotplugd.socket with default SocketMode that grants 0666 permissions, making it world-writable. This is used for the "/run/cloud-init/hook-hotplug-cmd" FIFO. An unprivileged user could trigger hotplug-hook commands.
Sensitive data could be exposed in logs of cloud-init before version 23.1.2. An attacker could use this information to find hashed passwords and possibly escalate their privilege.