What is the CVSS score of CVE-2026-34178?

CVE-2026-34178 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Canonical are affected by CVE-2026-34178?

Canonical LXD versions prior to 6.8 contain a critical privilege escalation vulnerability in backup import functionality that allows authenticated users to bypass project security restrictions and…. A patch is available.

How to fix or mitigate CVE-2026-34178?

Within 24 hours: Identify all LXD deployments running versions before 6.8 and restrict backup import operations to trusted sources only; document current version inventory. Within 7 days: Upgrade all LXD instances to version 6.8 or later per Canonical's security advisory. Within 30 days: Conduct access control audit of all project-restricted users and verify isolation boundaries on upgraded systems; implement enhanced logging and monitoring of backup import operations.

Canonical CVE-2026-34178

EUVD-2026-20874 CRITICAL

Improper Input Validation (CWE-20)

2026-04-09 canonical

GHSA-q96j-3fmm-7fv4

Authentication Bypass Canonical

9.1

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.1 CRITICAL

AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

SUSE

CRITICAL

qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Re-analysis Queued

Apr 22, 2026 - 21:07 vuln.today

cvss_changed

EUVD ID Assigned

Apr 09, 2026 - 09:30 euvd

EUVD-2026-20874

Analysis Generated

Apr 09, 2026 - 09:30 vuln.today

Patch released

Apr 09, 2026 - 09:30 nvd

Patch available

CVE Published

Apr 09, 2026 - 09:18 nvd

CRITICAL 9.1

DescriptionCVE.org

In Canonical LXD before 6.8, the backup import path validates project restrictions against backup/index.yaml in the supplied tar archive but creates the instance from backup/container/backup.yaml, a separate file in the same archive that is never checked against project restrictions. An authenticated remote attacker with instance-creation permission in a restricted project can craft a backup archive where backup.yaml carries restricted settings such as security.privileged=true or raw.lxc directives, bypassing all project restriction enforcement and allowing full host compromise.

AnalysisAI

Backup import in Canonical LXD before 6.8 bypasses project security restrictions, enabling privilege escalation to full host compromise. An authenticated remote attacker with instance-creation permission in a restricted project crafts malicious backup archives containing conflicting configuration files: backup/index.yaml passes validation, while backup/container/backup.yaml (never validated) carries forbidden directives like security.privileged=true or raw.lxc commands. Exploiting this dual-file validation gap allows unrestricted container creation that breaks isolation boundaries. No public exploit identified at time of analysis.

Technical ContextAI

Root cause: inconsistent validation logic (CWE-20). Import process validates project restrictions against backup/index.yaml but instantiates from backup/container/backup.yaml without restriction checks. Attacker-controlled discrepancy between these files in a single tar archive defeats enforcement, enabling injection of privileged container settings that should be blocked by project policies.

RemediationAI

Vendor-released patch: upgrade to Canonical LXD 6.8 or later, which enforces consistent validation of both backup/index.yaml and backup/container/backup.yaml against project restrictions. Upstream fix applied via https://github.com/canonical/lxd/pull/17921 detailed in security advisory https://github.com/canonical/lxd/security/advisories/GHSA-q96j-3fmm-7fv4. Until patching, implement workarounds: revoke instance-creation permissions in restricted projects for non-administrative users, prohibit backup imports from untrusted sources, or disable backup import functionality entirely via API access controls. Monitor LXD audit logs for anomalous backup restoration events targeting restricted projects.