# CVE-2026-34178: Canonical LXD project restriction bypass via crafted backup import

Source: https://junglewise.ai/threats/cve-2026-34178-canonical-lxd-project-restriction-bypass-via-crafted-backup  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-09. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-34178 · Severity: critical · CVSS 9.1 · Published 2026-04-09

LXD is a system container and virtual machine manager used to run isolated environments on Linux. A vulnerability in how LXD imports backup files allows a user with limited permissions to bypass security restrictions and gain full administrative control over the host server. By providing a specially crafted backup file, an attacker can create a container that has unauthorized access to the host's files and resources, potentially leading to a complete system takeover.

Technologies: [Canonical LXD](https://junglewise.ai/threats/technologies/lxd), [github.com/canonical/lxd (Go)](https://junglewise.ai/threats/technologies/github-com-canonical-lxd). Vendors: [Canonical](https://junglewise.ai/threats/vendors/canonical), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-34178 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34178 being exploited in the wild.

**How severe is CVE-2026-34178?** Critical severity, with a CVSS score of 9.1, published 9 April 2026.

**Which products and versions are affected?** Canonical LXD >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267; github.com/canonical/lxd (Go) >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267, SEMVER:introduced=0.0.0-20210305023314-538ac3df036e, SEMVER:introduced=0.0.0-20210305023314-538ac3df036e,last_affected=0.0.0-20260226085519-736f34afb267.

**Is there a fix for CVE-2026-34178?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-34178 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-34178?** Check whether you run Canonical LXD or github.com/canonical/lxd (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability arises from a discrepancy between two configuration files within a backup tar archive: 'backup/index.yaml' and 'backup/container/backup.yaml'. LXD's 'AllowInstanceCreation' function validates project restrictions (such as blocking privileged containers or host device passthrough) against 'index.yaml'. However, the actual instance is created using the configuration in 'backup.yaml', which is not re-validated against project-specific restrictions. An attacker with instance-creation rights in a restricted project can craft a backup where 'index.yaml' appears benign while 'backup.yaml' contains malicious configurations like 'security.privileged=true' or 'raw.lxc' host mounts. This allows for container escape and full host compromise. Patches are available in LXD series 5.0, 5.21, and 6.

## Affected products

- Canonical LXD >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267

## Identifiers

- CVE-2026-34178
- GHSA-q96j-3fmm-7fv4
- GO-2026-5576

## Timeline

- 2026-04-09: advisory: Initial GitHub Advisory published
- 2026-04-10: disclosed: Full advisory details and CVE-2026-34178 assigned

## References

- [https://api.github.com/users/mpurg](https://api.github.com/users/mpurg)
- [https://github.com/mpurg](https://github.com/mpurg)
- [https://api.github.com/users/mpurg/gists%7B/gist_id%7D](https://api.github.com/users/mpurg/gists%7B/gist_id%7D)
- [https://api.github.com/users/mpurg/repos](https://api.github.com/users/mpurg/repos)
- [https://avatars.githubusercontent.com/u/2342756?v=4](https://avatars.githubusercontent.com/u/2342756?v=4)
- [https://api.github.com/users/mpurg/events%7B/privacy%7D](https://api.github.com/users/mpurg/events%7B/privacy%7D)

## Related threats

- [LXD restricted project bypass leading to arbitrary command execution](https://junglewise.ai/threats/lxd-has-restricted-project-bypass-leading-to-arbitrary-command-9034cd45)
- [LXD project restriction bypass in custom volume copy](https://junglewise.ai/threats/lxd-has-project-restriction-bypass-for-custom-volume-copy-across-d414fa7a)
- [LXD project restriction bypass in instance copy](https://junglewise.ai/threats/lxd-has-project-restriction-bypass-in-instance-copy-across-projects-48d466e0)
- [Incus arbitrary file write via trusted image hash](https://junglewise.ai/threats/lxd-has-arbitrary-file-write-on-client-due-to-trusted-image-hash-072dacee)
- [LXD argument injection in backup compression algorithm](https://junglewise.ai/threats/lxd-has-argument-injection-in-backup-compression-algorithm-leading-to-50a60f2a)