EUVD-2026-43854
GHSA-h5g9-xf42-5xc8
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only post-foothold EoP so AV:L/PR:L; race-condition use-after-free gives AC:H; full kernel compromise yields C:H/I:H/A:H with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Secure Kernel Mode allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in Windows Secure Kernel Mode (VBS/Isolated User Mode trust boundary) affects Windows 11 24H2/25H2/26H1 and Windows Server 2025, where a use-after-free (CWE-416) lets an already-authenticated local attacker gain elevated privileges. Microsoft rates it 7.0 (High) with a local, high-complexity vector requiring low privileges and no user interaction. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to already have valid low-privileged local code execution on the target (PR:L), and requires an affected build of Windows 11 24H2/25H2/26H1 or Windows Server 2025 with Secure Kernel Mode / VBS active. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals are internally consistent and point to a real but not top-tier-urgent issue. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who has already obtained a low-privileged foothold on a Windows 11 24H2 or Windows Server 2025 host - for example via phishing, a compromised service account, or a low-priv RDP session - runs a local program that repeatedly races the vulnerable Secure Kernel Mode code path to trigger the use-after-free. After reclaiming the freed object with controlled data, they corrupt secure-kernel state to elevate to SYSTEM/kernel and undermine VBS protections. … |
| Remediation | Apply the Microsoft security update for CVE-2026-50392 as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50392 (Patch available per vendor advisory); the MSRC update guide lists the exact patched build number for each affected edition - deploy the current cumulative update for your Windows 11 24H2/25H2/26H1 or Windows Server 2025 branch. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all Windows 11 (versions 24H2, 25H2, 26H1) and Windows Server 2025 deployments in your environment and escalate them to critical remediation priority. …
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
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