CVE-2026-63343: Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Incusto a version that resolves this vulnerability.Fixed in 7.3.0
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated Incus user can exploit it by using a malicious image whose metadata.yaml is a symlink to an arbitrary host path. No user interaction is required.
Are Incus deployments affected by default?
The issue applies to Incus versions prior to 7.3.0 when an authenticated user can use a malicious image and access instance metadata through the API. The provided information does not identify any configuration prerequisite beyond that access.
What access can an attacker gain?
The attacker can read or overwrite arbitrary files on the host filesystem with root privileges through the instance metadata API. This can affect confidentiality, integrity, and availability beyond the Incus instance.
What should be done if patching cannot happen immediately?
The provided information does not specify a workaround. Until upgrading to 7.3.0, limit authenticated users' ability to introduce or use untrusted images and access instance metadata APIs where possible.