Canonical LXD up to 4.0.12/5.0.8/5.21.6/6.9 Instance Template Processing metadata.yaml os.Create path traversal

Summaryinfo

A vulnerability has been found in Canonical LXD up to 4.0.12/5.0.8/5.21.6/6.9 and classified as very critical. This issue affects the function os.Create of the file metadata.yaml of the component Instance Template Processing. The manipulation leads to path traversal. This vulnerability is uniquely identified as CVE-2026-66897. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Canonical LXD up to 4.0.12/5.0.8/5.21.6/6.9. This issue affects the function os.Create of the file metadata.yaml of the component Instance Template Processing. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-66897 since 07/28/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/24/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 4.0.13, 5.0.9, 5.21.7 or 6.10 eliminates this vulnerability.

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Productinfo

Vendor

• Canonical

Name

• LXD

Version

• 4.0.0
• 4.0.1
• 4.0.2
• 4.0.3
• 4.0.4
• 4.0.5
• 4.0.6
• 4.0.7
• 4.0.8
• 4.0.9
• 4.0.10
• 4.0.11
• 4.0.12
• 5.0.0
• 5.0.1
• 5.0.2
• 5.0.3
• 5.0.4
• 5.0.5
• 5.0.6
• 5.0.7
• 5.0.8
• 5.21.0
• 5.21.1
• 5.21.2
• 5.21.3
• 5.21.4
• 5.21.5
• 5.21.6
• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9

License

• open-source

Website

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

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