CVE-2026-66897
Instance template path traversal allows arbitrary host file write as root
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
9.9
Instance template path traversal allows arbitrary host file write as root
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
CVE-2026-66897- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-22, CWE-23
- Updated
- 2026-11-02
EUVDEUVD-2026-64757
9.9
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
EUVD-2026-64757- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Updated
- 2026-11-02
NVD
9.9
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
CVE-2026-66897- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-22, CWE-23
- Updated
- 2026-11-02
OSV
9.9
Instance template path traversal allows arbitrary host file write as root
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
CVE-2026-66897- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Weakness
- CWE-22, CWE-23
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-66897
9.9
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
DEBIAN-CVE-2026-66897- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-66897
9.9
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
- Record
UBUNTU-CVE-2026-66897- CVSS 3.1
- 9.9 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
lxdDebian:12 |
All versions, plus listed versions 5.0.2+git20231211.1364ae4-15.0.2+git20231211.1364ae4-25.0.2+git20231211.1364ae4-35.0.2+git20231211.1364ae4-45.0.2+git20231211.1364ae4-5 Show 12 moreShow less5.0.2+git20231211.1364ae4-65.0.2+git20231211.1364ae4-75.0.2+git20231211.1364ae4-85.0.2+git20231211.1364ae4-95.0.2-55.0.2-5+deb12u15.0.2-5+deb12u25.0.2-5+deb12u35.0.2-5+deb12u45.0.2-5+deb12u55.0.2-5+deb12u65.0.2-6 |
None known |
lxdDebian:13 |
All versions, plus listed versions 5.0.2+git20231211.1364ae4-95.0.2+git20231211.1364ae4-9+deb13u15.0.2+git20231211.1364ae4-9+deb13u25.0.2+git20231211.1364ae4-9+deb13u35.0.2+git20231211.1364ae4-9+deb13u45.0.2+git20231211.1364ae4-9+deb13u55.0.2+git20231211.1364ae4-9+deb13u65.0.2+git20231211.1364ae4-9+deb13u7 |
None known |
lxdUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 0.20-0ubuntu40.21-0ubuntu30.21-0ubuntu50.22-0ubuntu10.22-0ubuntu2 Show 45 moreShow less0.23-0ubuntu10.23-0ubuntu20.23-0ubuntu30.24-0ubuntu20.24-0ubuntu30.24-0ubuntu40.25-0ubuntu10.26-0ubuntu20.26-0ubuntu30.27-0ubuntu10.27-0ubuntu22.0.0~beta1-0ubuntu32.0.0~beta1-0ubuntu42.0.0~beta2-0ubuntu12.0.0~beta2-0ubuntu22.0.0~beta3-0ubuntu12.0.0~beta3-0ubuntu22.0.0~beta3-0ubuntu32.0.0~beta3-0ubuntu42.0.0~beta4-0ubuntu12.0.0~beta4-0ubuntu22.0.0~beta4-0ubuntu32.0.0~beta4-0ubuntu42.0.0~beta4-0ubuntu52.0.0~beta4-0ubuntu62.0.0~beta4-0ubuntu72.0.0~rc1-0ubuntu12.0.0~rc1-0ubuntu22.0.0~rc1-0ubuntu32.0.0~rc2-0ubuntu22.0.0~rc2-0ubuntu32.0.0~rc3-0ubuntu12.0.0~rc3-0ubuntu22.0.0~rc3-0ubuntu32.0.0~rc3-0ubuntu42.0.0~rc4-0ubuntu12.0.0~rc5-0ubuntu12.0.0~rc6-0ubuntu12.0.0~rc6-0ubuntu22.0.0~rc7-0ubuntu12.0.0~rc7-0ubuntu22.0.0~rc8-0ubuntu12.0.0~rc8-0ubuntu22.0.0~rc8-0ubuntu32.0.0~rc8-0ubuntu5 |
None known |
lxdUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 2.18-0ubuntu62.19-0ubuntu12.20-0ubuntu32.20-0ubuntu42.21-0ubuntu1 Show 18 moreShow less2.21-0ubuntu22.21-0ubuntu32.21-0ubuntu43.0.0~beta2-0ubuntu33.0.0~beta3-0ubuntu33.0.0~beta5-0ubuntu23.0.0~beta7-0ubuntu13.0.0-0ubuntu13.0.0-0ubuntu23.0.0-0ubuntu33.0.0-0ubuntu43.0.1-0ubuntu1~18.04.13.0.2-0ubuntu1~18.04.13.0.3-0ubuntu1~18.04.13.0.3-0ubuntu1~18.04.23.0.3-0ubuntu1~18.04.2+esm13.0.3-0ubuntu1~18.04.2+esm23.0.3-0ubuntu1~18.04.2+esm3 |
None known |
lxdUbuntu:20.04:LTS |
All versions, plus listed versions 1:0.71:0.81:0.91:0.10 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-66897 is a critical vulnerability (CVSS 9.9) in Canonical Lxd, published August 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.72%, the 53rd percentile. No source names a fixed version.
References
github.com/canonical/lxd/security/advisories/GHSA-q39m-8fx9-42fv
github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66897.json
nvd.nist.gov/vuln/detail/CVE-2026-66897
github.com/canonical/lxd
security-tracker.debian.org/tracker/CVE-2026-66897
ubuntu.com/security/CVE-2026-66897
cve.org/CVERecord?id=CVE-2026-66897
Left out here: 26 versions. The JSON record has them.