Vulnerability · Published Aug 21, 2026 · Assigned by GitHub_M
CVE-2026-63343Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
Critical 9.9
In plain English
A critical-severity security flaw in incus from lxc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | incus | 6.0.4-2+deb13u9 | DEBIAN-CVE-2026-63343 |
| Debian:14 | incus | 7.0.1-2 | DEBIAN-CVE-2026-63343 |
| Ubuntu:26.10 | incus | no fix listed | UBUNTU-CVE-2026-63343 |
Affected products (as reported)
Weakness: CWE-73 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/lxc/incus/security/advisories/GHSA-fmjx-5j3g-997p x_refsource_CONFIRM