CVE-2026-23953

Publication date 23 January 2026

Last updated 23 January 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

8.7 · High

Score breakdown

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.

Status

Package Ubuntu Release Status
incus 25.10 questing
Needs evaluation
24.04 LTS noble
Needs evaluation
22.04 LTS jammy Not in release
lxd 25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation

Severity score breakdown

Parameter Value
Base score 8.7 · High
Attack vector Adjacent
Attack complexity Low
Privileges required Low
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

References

Other references