LXD has arbitrary file read+write on host via rootfs/ symlink in malicious image

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Reported from https://github.com/lxc/incus/security/advisories/GHSA-2q3f-q5pq-g8wv

Summary A specially crafted image can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.

Details Incus validates an image as soon as it sees a normal `metadata.yaml` and a `rootfs/` entry, but full extraction can later process a duplicate top-level `rootfs` symlink. Later, the stopped-container file API opens `d.RootfsPath()` and passes that file descriptor to `forkfile`, which chroots to it. ``` metadata.yaml rootfs/ rootfs -> / ``` In practice, this allows a malicious actor to access the host's filesystem with root privileges.

PoC Below, we map the container's rootfs to `/` on the host, but it can be mapped anywhere. We then retrieve the host's `/etc/shadow` file and create a file in `/`. ``` #!/bin/sh set -eu tmpdir=$(mktemp -d) cleanup() { rm -rf "${tmpdir}" } trap cleanup EXIT INT QUIT TERM HUP mkdir -p "${tmpdir}/img/rootfs"…

Published by the source

6 Nov 2026, 19:36 UTC

Last modified by the source

6 Nov 2026, 19:45 UTC

Source last checked

7 Nov 2026, 06:05 UTC

1. Revision 2 · amended · 7 Nov 2026

   Amended from osv record GHSA-vghh-5rfx-xhq8

2. Revision 1 · created · 6 Nov 2026

   Published from ghsa record GHSA-vghh-5rfx-xhq8

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# Patch Next advisory brief: GHSA-vghh-5rfx-xhq8

Advisory: LXD has arbitrary file read+write on host via rootfs/ symlink in malicious image
IDs: GHSA-vghh-5rfx-xhq8
Record: https://patchnext.com/advisories/ghsa-vghh-5rfx-xhq8 (revision 2, source checked 7 Nov 2026, 06:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/canonical/lxd 0.0.0-20260630083100-c5184be310b1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/canonical/lxd: affected < 0.0.0-20260630083100-c5184be310b1; fixed in 0.0.0-20260630083100-c5184be310b1

## Suggested inspection (read-only)
- Go github.com/canonical/lxd: 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/canonical/lxd.
- 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-vghh-5rfx-xhq8 (GitHub-reviewed advisory GHSA-vghh-5rfx-xhq8 lists affected ranges: Go github.com/canonical/lxd >=0 <0.0.0-20260630083100-c5184be310b1)
- Verified: https://osv.dev/vulnerability/GHSA-vghh-5rfx-xhq8 (OSV record GHSA-vghh-5rfx-xhq8 lists affected ranges: Go github.com/canonical/lxd >=0 <0.0.0-20260630083100-c5184be310b1 (fixed))

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