Improper access control in LXD - CVE-2026-9640
Published: June 29, 2026
Vulnerability identifier: #VU135806
CSH Severity: Low
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-9640
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges to arbitrary host root.
The vulnerability exists due to improper access control in the instance-backup import and snapshot-restore handlers when importing a tampered backup and restoring a snapshot. A remote privileged user can upload a crafted instance backup containing restricted snapshot configuration and restore the malicious snapshot to escalate privileges to arbitrary host root.
Exploitation requires a hardened multi-tenant project with restricted=true and restricted.containers.lowlevel=block, and the ability to create instances and edit the target project.
Affected software
LXD
Debian Linux
lxd (Debian package)
Debian Linux
lxd (Debian package)
How to mitigate CVE-2026-9640
Install security update from vendor's website.
LXD - addressed in versions 5.0.7, 5.21.5, 6.9
lxd (Debian package) - update to 5.0.2+git20231211.1364ae4-9+deb13u7
lxd (Debian package) - update to 5.0.2+git20231211.1364ae4-9+deb13u7