EUVD-2026-43987
GHSA-62c2-hmjm-mpm6
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-privileged attacker (AV:L/PR:L) triggers a kernel UAF with no user interaction (AC:L/UI:N), yielding SYSTEM-level control and full C/I/A impact within the same system (S:U).
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
Use after free in Windows Kernel allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Microsoft Windows Kernel (Windows 11 version 26H1) lets an already-authenticated low-privileged user corrupt kernel memory through a use-after-free condition and gain SYSTEM-level control. Microsoft self-reported the flaw and has shipped a patch; there is no public exploit identified at time of analysis and it is not listed in CISA KEV. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to already have local, authenticated code execution at low privilege on the target (CVSS PR:L, AV:L) - this is a privilege-escalation flaw, not a remote entry point, so it cannot be triggered across the network or by a remote unauthenticated attacker. … 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, 7.8 High) describes a realistic and attractive local EoP primitive: low attack complexity, only low privileges needed, and no user interaction, but it requires the attacker to already be executing code on the target (AV:L). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who already has a standard (low-privileged) user session - obtained via phishing, a compromised service account, or a malicious app - runs a crafted program that rapidly frees and reallocates a specific kernel object to trigger the use-after-free, grooming the freed slot to overwrite its own process token and escalate to SYSTEM. No user interaction is required, and given the low attack complexity a reliable exploit is plausible, though no public POC is identified at time of analysis. |
| Remediation | Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-49173 via Windows Update or your patch-management system to all Windows 11 version 26H1 systems; the exact KB/build should be taken from the MSRC entry at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49173 (no standalone fix version string was provided in the input, so confirm the KB there before deployment). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify and inventory all Windows 11 version 26H1 systems in your environment and assess exposure based on your user access model and endpoint protection posture. …
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External POC / Exploit Code
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