CVE-2026-85526

CRITICALPre-NVD 9.99.9—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (41st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this weekElevated
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.9Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Path traversal in the Btrfs storage driver (unpackVolume) in Canonical LXD on Linux allows an authenticated user with instance creation privileges to delete or replace arbitrary files and directories on the host filesystem as root via a crafted subvolumes[].path entry in backup/optimized_header.yaml during a btrfs optimized backup import.

CVSS v3
9.9
EG Score
9.9CRITICALmedium confidence
EG Risk
61
EG Risk 61/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity99% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 28, 2026

Last Modified

September 29, 2026

Advisory Details (1)

Auto-updated Sep 29, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Path traversal via btrfs optimized-backup `subvolumes[].path` enables root file/dir manipulation · Advisory · canonical/lxd · GitHub

https://github.com/canonical/lxd/security/advisories/GHSA-h85r-gjgx-g2rv

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 17× in last 7d / 17× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-03 17:19 UTCEG score recompute
  2. 2026-10-03 14:26 UTCEPSS rescore
  3. 2026-10-02 21:10 UTCEG score recompute
  4. 2026-10-02 17:57 UTCEPSS rescore
  5. 2026-10-01 21:01 UTCEG score recompute
  6. 2026-10-01 19:50 UTCEPSS rescore
  7. 2026-09-30 16:16 UTCEG score recompute
  8. 2026-09-30 15:04 UTCEPSS rescore
  9. 2026-09-29 16:46 UTCEG score recompute
  10. 2026-09-29 04:31 UTCEG score recompute
  11. 2026-09-29 04:00 UTCEG score recompute
  12. 2026-09-28 23:33 UTCEG score recompute
  13. 2026-09-28 15:27 UTCEG score recompute
  14. 2026-09-28 14:24 UTCEG score recompute
  15. 2026-09-28 14:02 UTCEG score recompute
  16. 2026-09-28 13:27 UTCEG score recompute
  17. 2026-09-28 13:27 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-85526?
CVE-2026-85526 is a critical vulnerability published on September 28, 2026. Path traversal in the Btrfs storage driver (unpackVolume) in Canonical LXD on Linux allows an authenticated user with instance creation privileges to delete or replace arbitrary files and directories on the host filesystem as root via a crafted subvolumes[].path entry in…
When was CVE-2026-85526 disclosed?
CVE-2026-85526 was first published on September 28, 2026, with the most recent update on September 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-85526 actively exploited?
CVE-2026-85526 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-85526?
CVE-2026-85526 has a CVSS base score of 9.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-85526?
A fix for CVE-2026-85526 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-85526

Explore →

Is Your Infrastructure Affected by CVE-2026-85526?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs