LXD: Importing a crafted backup leads to project restriction bypass

Exploitation

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

CVSS

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

EPSS

• CVE-2026-34178: 0.42% estimated exploitation activity in the next 30 days; percentile 36.77 (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 LXD instance backup import validates project restrictions against backup/index.yaml embedded in the tar archive, but creates the actual instance from backup/container/backup.yaml extracted to the storage volume. Because these are separate, independently attacker-controlled files within the same tar archive, an attacker with instance-creation rights in a restricted project can craft a backup where index.yaml contains clean configuration (passing all restriction checks) while backup.yaml contains security.privileged=true, raw.lxc host filesystem mounts, and restricted device types. The instance is created from the unchecked backup.yaml, bypassing all project restriction enforcement. Details LXD projects support a restricted=true mode that enforces security boundaries on what instances within the project can do. These restrictions include blocking security.privileged=true containers, raw.lxc / raw.apparmor overrides, and device passthrough (GPU, USB, PCI, unix-char). These…

Published by the source

11 Aug 2026, 23:21 UTC

Last modified by the source

11 Aug 2026, 23:45 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-q96j-3fmm-7fv4

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GO-2026-5576

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# Patch Next advisory brief: CVE-2026-34178

Advisory: LXD: Importing a crafted backup leads to project restriction bypass
IDs: CVE-2026-34178, GHSA-q96j-3fmm-7fv4
Record: https://patchnext.com/advisories/cve-2026-34178 (revision 2, 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: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/canonical/lxd: affected >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## 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://osv.dev/vulnerability/GO-2026-5576 (OSV record GO-2026-5576 lists affected ranges: Go github.com/canonical/lxd >=0.0.0-20210305023314-538ac3df036e)
- Verified: https://github.com/advisories/GHSA-q96j-3fmm-7fv4 (GitHub-reviewed advisory GHSA-q96j-3fmm-7fv4 lists affected ranges: Go github.com/canonical/lxd >=0.0.0-20210305023314-538ac3df036e <=0.0.0-20260226085519-736f34afb267)

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