Vulnerability in Linuxcontainers Incus
CVE-2026-23953
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.
Vulnerability class: CRLF Injection
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (40.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000
Affected products
- Linuxcontainers Incus
- Lxc Incus — versions >= 6.1.0, <= 6.20.0, <= 6.0.5
Weakness classification (CWE)
References
- github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32 (Exploit, Vendor Advisory)
- github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go (Product)
- github.com/user-attachments/files/24473682/environment_newline_injection.sh (Exploit)
- github.com/user-attachments/files/24473685/environment_newline_injection.patch (Patch)
Frequently asked questions
- What is CVE-2026-23953?
- CVE-2026-23953 is a high-severity vulnerability in Linuxcontainers Incus, classified under CRLF Injection. CVSS score: 8.7/10. Published 2026-01-22.
- How severe is CVE-2026-23953?
- High severity. CVSS v3 base score is 8.7 out of 10.