What is CVE-2026-63300?

CVE-2026-63300 is a critical-severity vulnerability in Canonical Lxd, classified under Missing Authorization. CVSS score: 9.9/10. Published 2026-08-12.

How severe is CVE-2026-63300?

Critical severity. CVSS v3 base score is 9.9 out of 10.

Auth bypass in Canonical Lxd

CVE-2026-63300

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 restr…

Vulnerability class: Broken Access Control

CVSS v3 metric

CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

Affected products

Canonical Lxd — versions 5.0.0, 5.21.0, 6.0

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

security@ubuntu.com (vendor-advisory, vdb-entry)
security@ubuntu.com (patch)
security@ubuntu.com (patch)

Frequently asked questions

What is CVE-2026-63300?: CVE-2026-63300 is a critical-severity vulnerability in Canonical Lxd, classified under Missing Authorization. CVSS score: 9.9/10. Published 2026-08-12.
How severe is CVE-2026-63300?: Critical severity. CVSS v3 base score is 9.9 out of 10.