CVE-2026-63295: Project restriction `restricted.containers.privilege=isolated` bypassable by omitting `security.idmap.isolated`

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-12 · updated 2026-10-24
Weakness: CWE-863

Description

An authorization bypass vulnerability in LXD allows an authenticated attacker to bypass project-level container isolation restrictions. When a project is configured with restrictions on container privileges (such as enforcing restricted.containers.privilege=isolated), LXD fails to enforce the requirement if an instance configuration omits the security.idmap.isolated key. An attacker can exploit this flaw by creating or updating an instance without explicitly setting security.idmap.isolated, bypassing the target project's security constraints.

Affected products

Canonical LXD: from 4.0.0 before 4.0.12; from 5.0.0 before 5.0.8; from 5.1 before 5.21.6; from 6.0 before 6.10 — fixed in 4.0.12, 5.0.8, 5.21.6, 6.10

How to fix

Upgrade to a fixed version: Canonical LXD 4.0.12, 5.0.8, 5.21.6, 6.10. Check the vendor advisory for mitigations.

References

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