What’s Vulnerable › Vulnerabilities
CVE-2026-66897: Instance template path traversal allows arbitrary host file write as root
- Severity: critical (CVSS 9.9 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-08-24 · updated 2026-10-24
- Weakness: CWE-22
Description
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.
Affected products
- Canonical LXD: before 4.0.13; from 5.0.0 before 5.0.9; from 5.1 before 5.21.7; from 6.0 through 6.9 — fixed in 4.0.13, 5.0.9, 5.21.7
How to fix
Upgrade to a fixed version: Canonical LXD 4.0.13, 5.0.9, 5.21.7. Check the vendor advisory for mitigations.
References
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