EUVD-2026-56673
GHSA-8hfh-87m8-cxgq
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-privileged access required to reach HTTP.sys; AC:L reflects no race condition or complex configuration needed; full C/I/A impact on privilege escalation to SYSTEM.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via heap-based buffer overflow in the Windows HTTP.sys kernel-mode driver affects Windows 11 (23H2 through 26H1) and Windows Server 2022/2025. An authenticated low-privileged local attacker can exploit this flaw to gain SYSTEM-level privileges on the target machine. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a low-privileged authenticated account on the target Windows machine - either via interactive logon, RDP, or code execution under a limited-privilege process. … 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 scores 7.8, reflecting a local attack requiring only a low-privileged account but yielding full confidentiality, integrity, and availability impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the Microsoft security update that raises affected builds to or above the fix thresholds confirmed via EUVD-2026-56673: Windows 11 23H2 to 10.0.22631.7517 or later, Windows 11 24H2 and Windows Server 2025 to 10.0.26100.9168 or later (note: Windows Server 2025 fix version per EUVD is 10.0.26100.33296 - organizations should verify which update applies to their specific SKU via the MSRC advisory), Windows 11 25H2 to 10.0.26200.9168 or later, Windows 11 26H1 to 10.0.28000.2704 or later, and Windows Server 2022 to 10.0.20348.5499 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and inventory all Windows 11 and Windows Server 2022/2025 systems running versions 23H2 through 26H1 within your environment. …
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External POC / Exploit Code
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