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CVE-2026-63343— Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root

Quick assessment

Affected
lxc incus
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.

Incus 是一个系统容器和虚拟机管理器。在 7.3.0 版本之前，如果包含一个指向任意主机路径的 符号链接的恶意镜像，经过身份验证的 Incus 用户即可通过实例元数据 API，以 root 权限读取或覆写主机上的任意文件。 和 路径已在之前的版本中通过禁止使用 以及采用 限制机制进行了修复；但 未被包含在上述任何一项补丁中，因此仍可被利用。该漏洞已在 7.3.0 版本中修复。

CVSS 9.9 · Critical EPSS 0.48% · P40

Possible ATT&CK Techniques 1 AI

T1552.005 · Cloud Instance Metadata API

Affected Version Matrix 1

VendorProduct Version RangeStatus
lxc incus < 7.3.0 affected
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I. Basic Information for CVE-2026-63343

Vulnerability Information
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Vulnerability Title
Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
Source: CVE Program / CVE List V5
Vulnerability Description
Incus is a system container and virtual machine manager. Prior to version 7.3.0, a malicious image containing a `metadata.yaml` symlink pointing to an arbitrary host path allows an authenticated Incus user to read or overwrite any file on the host as root via the instance metadata API. The `exec-output` and `templates/` paths were patched in a prior release using `Lstat` rejection and `os.OpenRoot` confinement; `metadata.yaml` was not included in either patch and remains exploitable. Version 7.3.0 patches the issue.
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
文件名或路径的外部可控制
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
lxc incus < 7.3.0 -

II. Public POCs for CVE-2026-63343

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Qwen3.6-35B-A3B · 9407 chars
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Trigger conditions & impact
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Exploit chain & mitigation
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III. Intelligence Information for CVE-2026-63343

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Vendor Advisories for CVE-2026-63343 (1)

Same Patch Batch · lxc · 2026-08-21 · 18 CVEs total

CVE-2026-48750 9.9 CRITICAL Incus has an arbitrary file write on host via `exec-output` symlink in crafted image
CVE-2026-63125 9.9 CRITICAL Incus vulnerable to root RCE via image backup.yaml symlink
CVE-2026-48769 9.9 CRITICAL Incus has an arbitrary file write on its client due to trusted image hash
CVE-2026-48755 9.9 CRITICAL Incus has an argument injection in backup compression algorithm leading to AFW and ACE
CVE-2026-62867 9.9 CRITICAL Incus has an argument injection in storage volume block.create_options that leads to arbit
CVE-2026-62941 9.9 CRITICAL Incus: Cross-project instance copy bypasses target project restrictions via TOCTOU in conf
CVE-2026-62940 9.9 CRITICAL Incus has a project restriction bypass via instance migration config override
CVE-2026-48752 9.9 CRITICAL Incus has arbitrary file read+write on host via templates/ symlink in malicious image
CVE-2026-48751 9.9 CRITICAL Incus has a restricted project bypass leading to arbitrary command execution
CVE-2026-48753 9.9 CRITICAL Incus has an arbitrary file write via path traversal in S3 multipart upload
CVE-2026-48749 9.9 CRITICAL Incus has an arbitrary file read+write on host via rootfs/ symlink in malicious image
CVE-2026-55621 7.7 HIGH Incus has a project restriction bypass for custom volume copy across projects
CVE-2026-55622 7.7 HIGH Incus has a project restriction bypass in instance copy across projects
CVE-2026-47753 4.4 MEDIUM Incus has a Nil-Pointer Dereference Panic via Instance Backup Import (volume omitted)
CVE-2026-62313 4.3 MEDIUM Incus: Project restriction `restricted.containers.privilege=isolated` bypassable by omitti
CVE-2026-48756 2.1 LOW Incus: CreateCustomVolumeFromBackup nil-pointer dereference on volume_snapshots[*].expires
CVE-2026-48754 2.1 LOW Incus: Nil-pointer dereference in createDependentVolumesFromBackup on disk.{Volume,VolumeS

IV. Related Vulnerabilities

Same product: incus
Same vendor: lxc
Same weakness: CWE-73

V. Comments for CVE-2026-63343

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