CVE-2026-63300

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: 0.3%, top 79% of all CVEs by exploit prediction. 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
Elevated
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%CVSS: 9.9Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

An improper validation vulnerability in the instancePostMigration function in lxd/instance_post.go of LXD allows an authenticated attacker with can_create_instances permissions on a restricted project to bypass project-level security restrictions. When migrating an instance between projects, LXD fails to validate the instance's configuration against the target project's enforced restrictions (such as restricted.containers.lowlevel, restricted.devices.*, and restricted.networks.access). An attacker can exploit this by creating a disallowed or high-privilege instance in an unrestricted project and subsequently moving it into the restricted project.

CVSS v3
9.9
EG Score
9.9(medium)
EG Risk
61(Track*)
EG Risk 61/100SSVC: Track*

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%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

August 12, 2026

Last Modified

August 28, 2026

Advisory Details (3)

Auto-updated Aug 28, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github.
github Patch Available🟡 PoC Available

Cross-project instance move bypasses all project restrictions allowing host command execution · Advisory · canonical/lxd · GitHub

https://github.com/canonical/lxd/security/advisories/GHSA-5g5r-wh97-qcq2
github_pr

Enforce project restrictions during instance move (stable-5.21)

Fix merged in canonical/lxd PR #18651 on 2026-07-03 — awaiting tagged release

https://github.com/canonical/lxd/pull/18651
github_pr

Enforce project restrictions during instance move

Fix merged in canonical/lxd PR #18605 on 2026-07-02 — awaiting tagged release

https://github.com/canonical/lxd/pull/18605

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 36× 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. 2026-08-30 04:48 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-29 08:32 UTCEG score recompute
  4. 2026-08-28 21:42 UTCEPSS rescore
  5. 2026-08-27 16:34 UTCEG score recompute
  6. 2026-08-27 14:25 UTCEPSS rescore
  7. 2026-08-26 18:49 UTCEG score recompute
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 13:51 UTCEG score recompute
  10. 2026-08-25 13:49 UTCEPSS rescore
  11. 2026-08-24 17:17 UTCEG score recompute
  12. 2026-08-24 12:34 UTCEG score recompute
  13. 2026-08-23 04:00 UTCEG score recompute
  14. 2026-08-23 00:19 UTCEPSS rescore
  15. 2026-08-22 03:36 UTCEG score recompute
  16. 2026-08-21 23:49 UTCEPSS rescore
  17. 2026-08-20 23:02 UTCEG score recompute
  18. 2026-08-20 22:55 UTCEPSS rescore
  19. 2026-08-19 18:36 UTCEG score recompute
  20. 2026-08-19 17:04 UTCEPSS rescore
  21. 2026-08-18 17:16 UTCEG score recompute
  22. 2026-08-18 13:48 UTCEPSS rescore
  23. 2026-08-17 15:47 UTCEG score recompute
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-16 15:20 UTCEG score recompute
Show 11 more
  1. 2026-08-16 14:56 UTCEPSS rescore
  2. 2026-08-16 03:11 UTCEG score recompute
  3. 2026-08-15 02:53 UTCEG score recompute
  4. 2026-08-15 01:30 UTCEPSS rescore
  5. 2026-08-13 22:31 UTCEG score recompute
  6. 2026-08-13 22:00 UTCEPSS rescore
  7. 2026-08-13 05:19 UTCEG score recompute
  8. 2026-08-13 04:21 UTCEG score recompute
  9. 2026-08-12 20:20 UTCEG score recompute
  10. 2026-08-12 19:21 UTCEG score recompute
  11. 2026-08-12 19:20 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-63300?
CVE-2026-63300 is a critical vulnerability published on August 12, 2026. An improper validation vulnerability in the instancePostMigration function in lxd/instancepost.go of LXD allows an authenticated attacker with cancreate_instances permissions on a restricted project to bypass project-level security restrictions. When migrating an instance between projects, LXD…
When was CVE-2026-63300 disclosed?
CVE-2026-63300 was first published in the National Vulnerability Database on August 12, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63300 actively exploited?
CVE-2026-63300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.8% of all scored CVEs.
What is the CVSS score of CVE-2026-63300?
CVE-2026-63300 has a CVSS v3 base score of 9.9 (NVD).
How do I remediate CVE-2026-63300?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63300, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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