Description

Incus is a system container and virtual machine manager. In versions 6.20.0 and below, a user with the ability to launch a container with a custom YAML configuration (e.g a member of the ‘incus’ group) can create an environment variable containing newlines, which can be used to add additional configuration items in the container’s lxc.conf due to newline injection. This can allow adding arbitrary lifecycle hooks, ultimately resulting in arbitrary command execution on the host. Exploiting this issue on IncusOS requires a slight modification of the payload to change to a different writable directory for the validation step (e.g /tmp). This can be confirmed with a second container with /tmp mounted from the host (A privileged action for validation only). A fix is planned for versions 6.0.6 and 6.21.0, but they have not been released at the time of publication.

Weaknesses 1

Affected Products 2

References 4

• github.com https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go#L1081
  Product
• github.com https://github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32
  ExploitVendor Advisory
• github.com https://github.com/user-attachments/files/24473682/environment_newline_injection.sh
  Exploit
• github.com https://github.com/user-attachments/files/24473685/environment_newline_injection.patch
  Patch

Remediation

• github.com https://github.com/user-attachments/files/24473685/environment_newline_injection.patch
  Patch