EUVD-2026-43912
GHSA-jxj3-7969-pqhq
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local UAF EoP requiring a pre-existing low-privilege foothold (PR:L, AV:L) and winning a race/heap condition (AC:H), yielding full SYSTEM-level C/I/A impact.
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 Runtime allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Runtime (WinRT) affects a broad range of supported Windows client and server releases, from Windows 10 1809 and Windows Server 2019 through Windows 11 26H1 and Windows Server 2025. An authorized local attacker who can execute low-privilege code can trigger a use-after-free (CWE-416) memory-corruption condition to elevate privileges, yielding full confidentiality, integrity, and availability impact on the host. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to already possess local, low-privilege authenticated code-execution on the target (CVSS PR:L, AV:L) - this is a post-compromise privilege-escalation primitive, not a remote entry point. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score is 7.0 (High) with vector AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - local attack vector, high attack complexity, and low privileges required, but high impact across all three dimensions. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who already has a low-privileged foothold on a Windows host - for example via a phishing-delivered user-mode payload or a compromised standard account - invokes a vulnerable Windows Runtime code path and races to reuse a freed object, corrupting memory to escalate from the current user to SYSTEM. Given AC:H, the exploit likely needs multiple attempts to win the underlying race or heap-grooming condition, but success grants full control of the machine. … |
| Remediation | Apply the Microsoft security update for CVE-2026-50449 (Patch available per vendor advisory); consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50449 for the exact patched build number matching each affected release, as Microsoft ships these as cumulative updates rather than a single named version. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Windows 10 (build 1809 or later), Windows 11, Windows Server 2019, and Windows Server 2025 systems that support local user access or execute untrusted code, prioritizing high-value and data-handling environments. …
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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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