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

Severity: critical (CVSS 9.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-12 · updated 2026-10-24
Weakness: CWE-862

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.

Affected products

Canonical LXD: from 5.0.0 before 5.0.8; from 5.1 before 5.21.6; from 6.0 before 6.10 — fixed in 5.0.8, 5.21.6, 6.10

How to fix

Upgrade to a fixed version: Canonical LXD 5.0.8, 5.21.6, 6.10. Check the vendor advisory for mitigations.

References

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