External risk intelligence

LXD Arbitrary File Read Write via Symbolic Link in Image Import

CVE advisorySeverity: CRITICAL (CVSS 9.9)

CVE-2026-63293

LXD is typically deployed in internal or administrative environments rather than as a public-facing service. While the vulnerability is network-accessible, successful exploitation requires authentication to trigger image import workflows, limiting exposure to authorized users or controlled internal processes.

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A recently identified vulnerability in LXD, a container and virtual machine manager, could permit unauthorized access and modification of files on the host system. This issue arises from improper handling of image archives, specifically when a symbolic link within the archive's metadata is not correctly validated, potentially allowing an attacker to read or write sensitive host files. While the technology itself is critical for managing environments, the main concern is confirming its relevance and exposure within your specific deployments.

Unchecked links in container images allow host file access.
Confirms exposure to critical container management software.
Verify LXD use and assess potential host system impact.

Attack Path

How an attacker could exploit the issue

An attacker with limited access could exploit this vulnerability by creating a special image archive. When this archive is imported into LXD, the system fails to properly check a file within the archive. This allows the attacker to trick LXD into reading or writing arbitrary files on the host system, potentially leading to significant compromise.

Authenticated access to import images.
Importing a crafted image archive.
Arbitrary file read and write on host.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an authenticated attacker to read or write arbitrary files on the host system when importing or unpacking a specially crafted image archive. This is possible because LXD does not properly validate if the `metadata.yaml` file is a symbolic link during image import.

Host system files.
Crafted image archive import.
Unauthorized file access or modification.

Operational Fix

Recommended remediation, mitigation, and detection steps

Security and platform teams are likely responsible for addressing this vulnerability in LXD, as it impacts the core functionality of the containerization platform. The first practical step is to identify all LXD instances, determine their exposure and criticality, and then confirm ownership before planning remediation actions, prioritizing instances that are externally accessible or handle sensitive data.

Identify LXD instances and their exposure.
Confirm accountable owner and assess business impact.
Plan remediation based on risk and available maintenance windows.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is LXD and why is it used?

LXD is a next-generation system container and virtual machine manager. It provides a common interface to manage the full lifecycle of containers and VMs across various Linux distributions, acting as a lightweight alternative to traditional hypervisors for running isolated workloads or system services.

What does CWE-59 mean for CVE-2026-63293?

CWE-59 refers to 'Improper Link Resolution Before File Access.' In this vulnerability, LXD fails to verify if the metadata.yaml file within an image archive is a symbolic link. Because it doesn't check this, an attacker can create a link that points outside the intended directory, tricking the software into interacting with sensitive files on the host system instead of the archive itself.

How is this LXD vulnerability triggered?

An attacker triggers this by providing a specially crafted image archive for import into LXD. The vulnerability does not trigger during standard container operations or while images are idle; it specifically occurs during the unpacking phase when the system processes the malicious archive.

How does Halo Surface Signal categorize this risk?

Halo Surface Signal notes that while the vulnerability is network-accessible, it is categorized as 'Unlikely' because LXD is generally used in internal or administrative settings. Successful exploitation requires an attacker to already have authenticated access to trigger the image import process, meaning the risk is primarily relevant to environments where unauthorized users have sufficient permissions.

Do I need to act immediately on this LXD flaw?

Your first step is to inventory your infrastructure to identify all active LXD instances. Once identified, evaluate their exposure and the sensitivity of the data they handle. Prioritize instances that are reachable from outside your network or perform critical system functions for upcoming maintenance or security updates.

References

github.com/canonical/lxd/security/advisories/GHSA-j825-cg34-5fr5

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.