When instructing cloud-init to set a random password for a new user account, versions before 21.2 would write that password to the world-readable log file /var/log/cloud-init-output.log. This could allow a local user to log in as another user.
Information written to log files can be of a sensitive nature and give valuable guidance to an attacker or expose sensitive user information.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Cloud-init | Canonical | * | 21.2 (excluding) |
| Red Hat Enterprise Linux 8 | RedHat | cloud-init-0:20.3-10.el8_4.5 | * |
| Red Hat Enterprise Linux 8.1 Extended Update Support | RedHat | cloud-init-0:18.5-7.el8_1.6 | * |
| Red Hat Enterprise Linux 8.2 Extended Update Support | RedHat | cloud-init-0:18.5-12.el8_2.10 | * |
| Cloud-init | Ubuntu | bionic | * |
| Cloud-init | Ubuntu | focal | * |
| Cloud-init | Ubuntu | groovy | * |
| Cloud-init | Ubuntu | trusty | * |
| Cloud-init | Ubuntu | upstream | * |
| Cloud-init | Ubuntu | xenial | * |
While logging all information may be helpful during development stages, it is important that logging levels be set appropriately before a product ships so that sensitive user data and system information are not accidentally exposed to potential attackers. Different log files may be produced and stored for: