NVD / CVE Program· CNA canonical

CVE-2026-66897: Instance template path traversal allows arbitrary host file write as root

CriticalCVSS 9.9 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.71% (FIRST EPSS); higher than 54.3% of all records.
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Canonical LXD 4.0.13, 5.0.9, 5.21.7.

Low priority for now. Upgrade to Canonical LXD 4.0.13, 5.0.9, 5.21.7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Path traversal

EUVD-2026-64757

Published: Aug 24, 2026
Updated: Oct 24, 2026
EPSS: 0.7% · 54th percentile
CWE: CWE-22

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 39 / 40 · 9.9 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.7%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · canonical: 9.9; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
canonical	lxd	cpe:2.3:a:canonical:lxd

Versions reported by the vendor

Affected version ranges reported by the assigning authority (canonical). Independent of NVD's CPE analysis and usually ahead of it.

Canonical LXD
- 4.0.0 and later · before 4.0.13affected · semver
- 5.0.0 and later · before 5.0.9affected · semver
- 5.21.0 and later · before 5.21.7affected · semver
- 6.0 and later · before 6.10affected · semver

Affected versions · NVD (4)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

canonical lxdbefore 4.0.13
canonical lxd5.0.0 and later · before 5.0.9
canonical lxd5.1 and later · before 5.21.7
canonical lxd6.0 and later · up to 6.9 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	lxd	from 0	—

Same product

canonical: all records

Other highest-scoring records for the same primary product.

CVE-2026-112816Improper certificate validation in the HTTPS listener in LXD
40Plan
CVE-2026-87799Arbitrary file write on LXD host via symlink in migration stream
39Monitor
CVE-2026-85526Path traversal via Btrfs optimized-backup subvolumes[].path enables root file/dir manipulation in LXD
39Monitor

Published before and after this one in the same product

← EarlierCVE-2026-16033Aug 12, 2026 · Arbitrary file read+write on host via templates/ symlink in malicious image
34Monitor
← EarlierCVE-2026-66898Aug 12, 2026 · Path traversal via unvalidated instance name in backup tarball restore enables root file write / RCE
39Monitor
Later →CVE-2026-85185Sep 28, 2026 · Path traversal in LXD btrfs storage driver allows arbitrary file deletion and write on host as root
38Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Canonical LXD	4.0.13	Vendor (CNA)
Canonical LXD	5.0.9	Vendor (CNA)
Canonical LXD	5.21.7	Vendor (CNA)
Canonical LXD	6.10	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-6689812 days apartPath traversal via unvalidated instance name in backup tarball restore enables root file write / RCE
39Monitor
CVE-2026-8552635 days apartPath traversal via Btrfs optimized-backup subvolumes[].path enables root file/dir manipulation in LXD
39Monitor
CVE-2026-8518535 days apartPath traversal in LXD btrfs storage driver allows arbitrary file deletion and write on host as root
38Monitor
CVE-2026-1603312 days apartArbitrary file read+write on host via templates/ symlink in malicious image
34Monitor
CVE-2025-54293326 days apartPath Traversal in LXD Instance Log File Retrieval
28Monitor
CVE-2025-54292326 days apartClient-Side Path Traversal in LXD-UI
19Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-secondary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1const file = path.join(ROOT, req.query.name);
2res.sendFile(file);

Fixed

1const file = path.resolve(ROOT, req.query.name);
2if (!file.startsWith(ROOT + path.sep)) {
3  return res.sendStatus(400);
4}
5res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:10 PM UTC

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