CVE-2026-66897: A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit pe

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CRITICAL 9.9UPGRADE

CVE-2026-66897 is a critical-severity flaw (CVSS 9.9) affecting lxd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 dis

Why this priority

Critical severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-22, CWE-23
Published	2026-08-24
Last modified	2026-10-23

Publisher (CNA): Canonical Ltd. · Vendor: canonical

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-24 10:16 UTCPublished CVE record published
2026-10-23 23:10 UTCUpdated Record last modified

canonical lxd UPGRADE

Affected: < 4.0.13 · >= 5.0.0 and < 5.0.9 · >= 5.1 and < 5.21.7 · >= 6.0 and <= 6.9

Fixed in: 4.0.13, 5.0.9, 5.21.7

Safe to downgrade to: a release before 5.0.0

1. Check installed version

apt-cache policy lxd || rpm -q lxd || lxd --version

2. UPGRADE to 4.0.13 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade lxd

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lxd

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.0.0 (Debian / Ubuntu)

apt-cache madison lxd sudo apt install lxd=<VERSION_BEFORE_5.0.0> sudo apt-mark hold lxd

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list lxd sudo dnf downgrade lxd-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add lxd

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · python-openslide · FIXED · 1.4.7-1.fc46 · FEDORA-2026-336bea884e · source

sudo dnf upgrade --advisory=FEDORA-2026-336bea884e

Fedora ELN · valgrind · FIXED · 3.28.0-1.eln159 · FEDORA-2026-c593ef1d15 · source

sudo dnf upgrade --advisory=FEDORA-2026-c593ef1d15

Debian 12 · lxd · NO FIX YET

Debian 13 · lxd · NO FIX YET

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/canonical/lxd/security/advisories/GHSA-q39m-8fx9-42fv

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-66897?

lxd: upgrade to 4.0.13, 5.0.9, 5.21.7. Exact commands for each OS are on this page.

Is CVE-2026-66897 being exploited?

CVE-2026-66897 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-66897 affect?

CVE-2026-66897 affects lxd. Severity is critical (CVSS 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

How urgent is CVE-2026-66897?

Priority 53/100. Critical severity; Public exploit reference

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References

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