CVE-2026-66897
CriticalCVSS 9.9Summary
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.
Risk Assessment
The risk includes full host takeover by an attacker, which can lead to system integrity compromise, data theft, or further attacks. The vulnerability can be exploited remotely by a user with container permissions.
Recommendation
It is recommended to immediately update LXD to a version that fixes this vulnerability and restrict container edit permissions and image launching to trusted users only.
Original NVD description (English source)
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.