EUVD-2026-43821
GHSA-42jq-q72w-7j5j
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local privilege escalation requiring an existing low-privileged session (AV:L, PR:L), no user interaction and low complexity (UI:N, AC:L), yielding full SYSTEM compromise (C/I/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Missing authentication for critical function in Windows Spaceport.sys allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Spaceport.sys Storage Spaces driver lets an already-authenticated low-privileged user gain SYSTEM-level control across Windows 10, Windows 11, and Windows Server 2016 through 2025. The flaw stems from a missing authentication check on a critical driver function (CWE-306), and Microsoft has released a patch; no public exploit has been identified at time of analysis. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must already possess a valid low-privileged local account and an interactive or programmatic session on the target Windows host (CVSS PR:L, AV:L), and the Storage Spaces driver Spaceport.sys must be present and loaded - which it is by default on all supported Windows 10, Windows 11, and Windows Server 2016-2025 systems. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, score 7.8 High) describes a low-complexity local attack requiring only an existing low-privilege account and no user interaction, yielding full compromise of the host - a classic post-exploitation privilege-escalation profile. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who has already gained a foothold as a standard user - for example via a phishing payload or a compromised low-privilege service account - invokes the unauthenticated critical function exposed by Spaceport.sys to elevate to SYSTEM. Because the attack is local, low-complexity, and needs no user interaction, it is well suited to automated post-exploitation tooling; no public exploit code has been identified at time of analysis, so this would require original exploit development. |
| Remediation | Patch available per vendor advisory: apply Microsoft's security update for CVE-2026-50333 from the MSRC Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50333, selecting the correct cumulative update for each affected Windows 10, Windows 11, and Windows Server build; the exact patched version numbers should be taken from that advisory rather than assumed. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all Windows 10, Windows 11, and Windows Server (2016 through 2025) systems and prioritize machines supporting user logins or privileged accounts. …
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External POC / Exploit Code
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