Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linuxcontainers | Incus | <= 6.0.5 |
Related Weaknesses (CWE)
References
- https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lProduct
- https://github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32ExploitVendor Advisory
- https://github.com/user-attachments/files/24473682/environment_newline_injectionExploit
- https://github.com/user-attachments/files/24473685/environment_newline_injectionPatch
FAQ
What is CVE-2026-23953?
CVE-2026-23953 is a vulnerability with a CVSS score of 8.7 (HIGH). 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...
How severe is CVE-2026-23953?
CVE-2026-23953 has been rated HIGH with a CVSS base score of 8.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-23953?
Check the references section above for vendor advisories and patch information. Affected products include: Linuxcontainers Incus.