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CVE-2026-66897— Instance template path traversal allows arbitrary host file write as root

Quick assessment

Affected
Canonical LXD
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

LXD 的实例模板处理过程中存在路径遍历漏洞。拥有容器编辑权限的攻击者，或任何用户通过构造恶意镜像，均可利用该漏洞以 root 权限覆盖宿主机上的任意文件。 在处理 中指定的目标模板路径时，LXD 会使用受限的 目录句柄对路径进行验证。然而，在后续步骤中，LXD 却使用未受限制的路径字符串调用 来打开和创建文件。路径解析检查与文件创建操作之间的不一致，使得攻击者能够突破目录限制，覆盖以 root 权限拥有的宿主机文件，从而实现宿主机上的 root 代码执行。

CVSS 9.9 · Critical EPSS 0.62% · P47

Affected Version Matrix 4

VendorProduct Version RangeStatus
Canonical LXD 4.0.0< 4.0.13 affected
5.0.0< 5.0.9 affected
5.21.0< 5.21.7 affected
6.0< 6.10 affected
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I. Basic Information for CVE-2026-66897

Vulnerability Information
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Vulnerability Title
Instance template path traversal allows arbitrary host file write as root
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Canonical LXD 4.0.0 ~ 4.0.13 -

II. Public POCs for CVE-2026-66897

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 14236 chars
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III. Intelligence Information for CVE-2026-66897

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Vendor Advisories for CVE-2026-66897 (1)

IV. Related Vulnerabilities

Same product: LXD
Same vendor: Canonical
Same weakness: CWE-22

V. Comments for CVE-2026-66897

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