Canonical LXD up to 5.0.6/5.21.4/6.7.x permissions.go isVMLowLevelOptionForbidden incomplete blacklist

Summaryinfo

A vulnerability classified as critical has been found in Canonical LXD up to 5.0.6/5.21.4/6.7.x. Affected is the function isVMLowLevelOptionForbidden of the file lxd/project/limits/permissions.go. This manipulation causes incomplete blacklist. The identification of this vulnerability is CVE-2026-34177. It is possible to initiate the attack remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Canonical LXD up to 5.0.6/5.21.4/6.7.x. Affected by this vulnerability is the function isVMLowLevelOptionForbidden of the file lxd/project/limits/permissions.go. The manipulation with an unknown input leads to a incomplete blacklist vulnerability. The CWE definition for the vulnerability is CWE-184. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Canonical LXD versions 4.12 through 6.7 contain an incomplete denylist in isVMLowLevelOptionForbidden (lxd/project/limits/permissions.go), which omits raw.apparmor and raw.qemu.conf from the set of keys blocked under the restricted.virtual-machines.lowlevel=block project restriction. A remote attacker with can_edit permission on a VM instance in a restricted project can inject an AppArmor rule and a QEMU chardev configuration that bridges the LXD Unix socket into the guest VM, enabling privilege escalation to LXD cluster administrator and subsequently to host root.

The weakness was shared by Miha Purg. The advisory is shared at github.com. This vulnerability is known as CVE-2026-34177 since 03/26/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1562.006 for this issue.

Upgrading to version 5.0.7, 5.21.5 or 6.8.0 eliminates this vulnerability.

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Productinfo

Vendor

• Canonical

Name

• LXD

Version

• 5.0.0
• 5.0.1
• 5.0.2
• 5.0.3
• 5.0.4
• 5.0.5
• 5.0.6
• 5.21.0
• 5.21.1
• 5.21.2
• 5.21.3
• 5.21.4
• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7

License

• open-source

Website

• Product: https://github.com/canonical/lxd/

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