CVE-2026-63343 Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
Authenticated users can read or overwrite arbitrary host files as root via a malicious metadata.yaml symlink in an image.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63343?
CVE-2026-63343 is a critical path traversal vulnerability in lxc incus, published on 21 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-73
Which versions are affected by CVE-2026-63343?
How do I fix CVE-2026-63343?
Upgrade to a fixed version.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-63343 being exploited?
There is no known exploitation of CVE-2026-63343 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-63343, GHSA-fmjx-5j3g-997p, UBUNTU-CVE-2026-63343.