CVE-2026-63300: An improper validation vulnerability in the instancePostMigration function in lxd/instance_post.go of LXD allows an…
CVE-2026-63300 · Severity: critical · CVSS 9.9 · Published 2026-08-12
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.
No. Junglewise Threat Intelligence has no report of CVE-2026-63300 being exploited in the wild.
How severe is CVE-2026-63300?
Critical severity, with a CVSS score of 9.9, published 12 August 2026.
Which products and versions are affected?
Canonical LXD. The advisory does not name versions.
Is there a fix for CVE-2026-63300?
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.
Am I affected by CVE-2026-63300?
Check whether you run Canonical LXD. 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.