CVE-2026-87799

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: 0.4% (32nd 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 week
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 9.9Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Improper link resolution in the migration receive path in Canonical LXD versions 4.0 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client that can create instances or custom storage volumes in a project, or a malicious migration source server, to write attacker-controlled files to arbitrary paths on the target host as root, leading to full host compromise. The attacker does this with a crafted rsync or btrfs send stream that plants a symlink in the transferred volume, such as rootfs or root.img, and then writes through it.

CVSS v3
9.9
EG Score
9.9CRITICALmedium confidence
EG Risk
45
EG Risk 45/100CISA 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%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
32nd
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (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
Patch available. Sources: github.
github Patch Available

Arbitrary file write on host via symlink in migration stream · Advisory · canonical/lxd · GitHub

https://github.com/canonical/lxd/security/advisories/GHSA-fmc3-3cpq-6whr

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 15× 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 16:24 UTCEG score recompute
  2. 2026-10-02 19:17 UTCEG score recompute
  3. 2026-10-01 22:11 UTCEG score recompute
  4. 2026-10-01 19:51 UTCEPSS rescore
  5. 2026-09-30 16:37 UTCEG score recompute
  6. 2026-09-30 15:04 UTCEPSS rescore
  7. 2026-09-29 17:13 UTCEG score recompute
  8. 2026-09-29 04:31 UTCEG score recompute
  9. 2026-09-29 04:00 UTCEG score recompute
  10. 2026-09-28 21:48 UTCEG score recompute
  11. 2026-09-28 17:36 UTCEG score recompute
  12. 2026-09-28 16:42 UTCEG score recompute
  13. 2026-09-28 14:24 UTCEG score recompute
  14. 2026-09-28 13:27 UTCEG score recompute
  15. 2026-09-28 13:27 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-87799?
CVE-2026-87799 is a critical vulnerability published on September 28, 2026. Improper link resolution in the migration receive path in Canonical LXD versions 4.0 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client that can create instances or custom storage volumes in a project, or a malicious migration source server, to write…
When was CVE-2026-87799 disclosed?
CVE-2026-87799 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-2026-87799 actively exploited?
CVE-2026-87799 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (32nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-87799?
CVE-2026-87799 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-2026-87799?
A fix for CVE-2026-87799 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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