SB20260629104 - Authorization bypass through user-controlled key in LXD

Description

This security bulletin contains information about 1 vulnerability.

1) Authorization bypass through user-controlled key (CVE-ID: CVE-2026-12411)

CWE-ID: CWE-639 - Authorization Bypass Through User-Controlled Key

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to read and modify another guest's custom storage volume data.

The vulnerability exists due to authorization bypass through a user-controlled key in the DevLXD instance device-update path when processing device PATCH requests that attach custom storage volumes. A local user can name another guest's volume in a crafted device PATCH request to read and modify another guest's custom storage volume data.

Only projects with security.devlxd.management.volumes enabled are vulnerable, and the issue affects cross-guest access within the same project without user interaction.

Remediation

Install update from vendor's website.

References

• https://github.com/canonical/lxd/security/advisories/GHSA-hhf9-qw4v-72xp
• https://github.com/canonical/lxd/blob/d29ece6284a78e6c21d276be4e5fb6fef697c35e/lxd/devlxd_instances.go#L88