How severe is CVE-2026-66897?

CVE-2026-66897 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-66897 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-66897?

CVE-2026-66897 affects Canonical Lxd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-66897?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-66897 published?

CVE-2026-66897 was published on 2026-08-24 and last updated on 2026-09-11.

CVE-2026-66897

CVE-2026-66897 is a critical-severity vulnerability in Canonical Lxd with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: Critical (CVSS 3.x base score 9.9)
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Canonical Lxd
Published: 2026-08-24
Last modified: 2026-09-11

Description

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.

Frequently asked questions

What is CVE-2026-66897?: 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.
How severe is CVE-2026-66897?: CVE-2026-66897 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-66897 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-66897?: CVE-2026-66897 affects Canonical Lxd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-66897?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-66897 published?: CVE-2026-66897 was published on 2026-08-24 and last updated on 2026-09-11.

References

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

Affected products (1)

cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*

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