Vulnerability · Published Jan 22, 2026 · Assigned by GitHub_M
CVE-2026-23953Incus container environment configuration newline injection
High 8.7
In plain English
A high-severity security flaw in incus from lxc. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | incus | 6.0.5-r6 | ALPINE-CVE-2026-23953 |
| Alpine:v3.24 | incus | 6.0.5-r6 | ALPINE-CVE-2026-23953 |
| Alpine:v3.23 | incus-feature | 6.21.0-r0 | ALPINE-CVE-2026-23953 |
| Alpine:v3.24 | incus-feature | 6.21.0-r0 | ALPINE-CVE-2026-23953 |
| Debian:13 | incus | 6.0.4-2+deb13u4 | DEBIAN-CVE-2026-23953 |
| Debian:13 | incus | 6.0.4-2+deb13u4 | DSA-6109-1 |
| Debian:14 | incus | 6.0.5-8 | DEBIAN-CVE-2026-23953 |
| Debian:12 | lxd | 5.0.2-5+deb12u3 | DSA-6153-1 |
| Debian:12 | lxd | no fix listed | DEBIAN-CVE-2026-23953 |
| Debian:13 | lxd | 5.0.2+git20231211.1364ae4-9+deb13u3 | DSA-6153-1 |
| Debian:13 | lxd | 5.0.2+git20231211.1364ae4-9+deb13u3 | DEBIAN-CVE-2026-23953 |
| Go | github.com/lxc/incus | no fix listed | GO-2026-4359 |
| Go | github.com/lxc/incus/v6 | 6.21.0 | GHSA-x6jc-phwx-hp32 |
| Go | github.com/lxc/incus/v6 | no fix listed | GO-2026-4359 |
| Ubuntu:25.10 | incus | no fix listed | UBUNTU-CVE-2026-23953 |
Affected products (as reported)
Weakness: CWE-93 · Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
References
- https://github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32 x_refsource_CONFIRM
- https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go#L1081 x_refsource_MISC
- https://github.com/user-attachments/files/24473682/environment_newline_injection.sh x_refsource_MISC
- https://github.com/user-attachments/files/24473685/environment_newline_injection.patch x_refsource_MISC