CVE-2026-63343: CWE-73: External Control of File Name or Path in lxc incus
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.
AI Analysis
Technical Summary
CVE-2026-63343 is an external control of file name or path vulnerability (CWE-73) in Incus prior to version 7.3.0. The flaw arises because a malicious container image can include a metadata.yaml symlink pointing to arbitrary host paths. When processed by the instance metadata API, this allows an authenticated Incus user to read or overwrite any file on the host with root privileges. Previous patches addressed similar vulnerabilities in exec-output and templates/ paths by using Lstat rejection and os.OpenRoot confinement, but did not cover metadata.yaml. The vulnerability is patched in Incus version 7.3.0.
Potential Impact
An authenticated user with access to Incus can exploit this vulnerability to gain root-level read and write access to arbitrary files on the host system. This can lead to full system compromise, data corruption, or unauthorized data disclosure. The CVSS score of 9.9 reflects the critical severity and the potential for complete system control.
Mitigation Recommendations
Upgrade Incus to version 7.3.0 or later, where this vulnerability is patched. There is no official fix or temporary workaround available for versions prior to 7.3.0. Until upgraded, restrict authenticated user access to trusted users only to minimize risk.
CVE-2026-63343: CWE-73: External Control of File Name or Path in lxc incus
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.
CVSS v3.1
Score 9.9critical
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-63343 is an external control of file name or path vulnerability (CWE-73) in Incus prior to version 7.3.0. The flaw arises because a malicious container image can include a metadata.yaml symlink pointing to arbitrary host paths. When processed by the instance metadata API, this allows an authenticated Incus user to read or overwrite any file on the host with root privileges. Previous patches addressed similar vulnerabilities in exec-output and templates/ paths by using Lstat rejection and os.OpenRoot confinement, but did not cover metadata.yaml. The vulnerability is patched in Incus version 7.3.0.
Potential Impact
An authenticated user with access to Incus can exploit this vulnerability to gain root-level read and write access to arbitrary files on the host system. This can lead to full system compromise, data corruption, or unauthorized data disclosure. The CVSS score of 9.9 reflects the critical severity and the potential for complete system control.
Mitigation Recommendations
Upgrade Incus to version 7.3.0 or later, where this vulnerability is patched. There is no official fix or temporary workaround available for versions prior to 7.3.0. Until upgraded, restrict authenticated user access to trusted users only to minimize risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-16T14:14:24.385Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a8869e8acd9273b494e470d
Added to database: 08/21/2026, 15:08:24 UTC
Last enriched: 08/21/2026, 15:23:43 UTC
Last updated: 08/22/2026, 03:21:01 UTC
Views: 8
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.