CVE-2026-34178: Importing a crafted backup leads to project restriction bypass

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-09 · updated 2026-10-26
Weakness: CWE-20

Description

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.

Affected products

Canonical LXD: from 4.12 through 5.0.6; from 5.21.0 through 5.21.4; from 6.0 through 6.7

References

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