Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA incus (lxc) Fixed in 7.3.0
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-63343
References
More lxc vulnerabilities
- TI-2019-04061 runc through 1.0-rc6, as used in Docker before 18.09.2 and other products, allows… CVSS 3.1HIGH 8.6
- TI-2026-45063 Incus vulnerable to root RCE via image backup.yaml symlink CVSS 3.1CRITICAL 9.9
- TI-2026-44978 Incus: Cross-project instance copy bypasses target project restrictions via TOCTOU in config merge CVSS 3.1CRITICAL 9.9
- TI-2026-36039 Incus has an arbitrary file write on its client due to trusted image hash CVSS 3.1CRITICAL 9.9
- TI-2026-36024 Incus has an arbitrary file write via path traversal in S3 multipart upload CVSS 3.1CRITICAL 9.9
- TI-2026-36022 Incus has a restricted project bypass leading to arbitrary command execution CVSS 3.1CRITICAL 9.9
Sources
- CVE-2026-63343 · CVE Program
- CVE-2026-63343 · NVD
- FIRST EPSS
- CVE-2026-63343 · Red Hat security data · CC BY 4.0
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