Incus container environment configuration newline injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.7 · CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-23953: 0.49% estimated exploitation activity in the next 30 days; percentile 42.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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 the newline injection. This can allow adding arbitrary lifecycle hooks, ultimately resulting in arbitrary command execution on the host. Details When passing environment variables in the config block of a new container, values are not checked for the presence of newlines [1], which can result in newline injection inside the generated container lxc.conf. This can be used to set arbitrary additional configuration items, such as lxc.hook.pre-start. By exploiting this, a user with the ability to launch a container with an arbitrary config can achieve arbitrary command execution as root on the host. Exploiting this issue on IncusOS requires a slight modification of the payload to change to a different writable directory for…

Published by the source

22 Jan 2026, 20:21 UTC

Last modified by the source

27 Mar 2026, 22:13 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x6jc-phwx-hp32

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# Patch Next advisory brief: CVE-2026-23953

Advisory: Incus container environment configuration newline injection
IDs: CVE-2026-23953, GHSA-x6jc-phwx-hp32
Record: https://patchnext.com/advisories/cve-2026-23953 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/lxc/incus/v6 6.21.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lxc/incus/v6: affected < 6.21.0; fixed in 6.21.0

## Suggested inspection (read-only)
- Go github.com/lxc/incus/v6: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/lxc/incus/v6.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x6jc-phwx-hp32 (GitHub-reviewed advisory GHSA-x6jc-phwx-hp32 lists affected ranges: Go github.com/lxc/incus/v6 >=0 <6.21.0)

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