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.

CVE-2026-63343 affects Incus, a system container and virtual machine manager, in versions prior to 7.3.0. A malicious container image can include a metadata.yaml file that is actually a symlink pointing to an arbitrary path on the host system. An authenticated Incus user can exploit this via the instance metadata API to read or overwrite any file on the host with root privileges. Previous patches addressed similar issues in exec-output and templates/ paths using Lstat rejection and os.OpenRoot confinement, but metadata.yaml was not covered. The vulnerability represents a symlink-based path traversal leading to privilege escalation and potential full host compromise. The fix was introduced in Incus version 7.3.0. The issue is tracked under GitHub Security Advisory GHSA-fmjx-5j3g-997p.