EUVD-2026-43813
GHSA-m293-66rr-7hmg
Severity by source
AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Local privilege escalation presumes an existing low-privileged foothold (PR:L) and kernel UAF yields full ring-0 impact; scope kept Unchanged as the kernel is the same authority.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Kernel allows an unauthorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Microsoft Windows Kernel allows an unauthorized attacker to gain elevated (SYSTEM-level) privileges by triggering a use-after-free condition (CWE-416) in kernel memory. The flaw affects a broad range of supported Windows client and server releases, from Windows 10 1607 and Windows Server 2012 through Windows 11 26H1 and Windows Server 2025. Microsoft has released a patch; there is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.
Technical ContextAI
The vulnerability resides in the Windows NT kernel (ntoskrnl / kernel-mode components), the most privileged and trusted layer of the operating system. The root cause is a use-after-free (CWE-416), in which a kernel object is freed while a dangling reference to it remains reachable; subsequent reuse of the freed allocation lets an attacker control the contents at that address and corrupt kernel memory. Per the supplied CPE data, the affected code is present across Microsoft's kernel from legacy servicing branches (Windows 10 1607/1809, Windows Server 2012 and 2012 R2) up to current releases (Windows 11 24H2/25H2/26H1, Windows Server 2022/2025), indicating a long-lived code path in a shared kernel component rather than a version-specific feature. Because the kernel enforces the security boundary between user-mode and ring 0, memory corruption here directly translates into a full compromise of the privilege model.
RemediationAI
Apply the Microsoft security update for CVE-2026-49798 as the primary remediation; Patch available per vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49798, where Microsoft publishes the exact KB article and fixed build number for each affected Windows client and server SKU - deploy the corresponding cumulative update for your specific version and prioritize internet-facing and multi-user systems. Because the fix is a kernel patch delivered through standard monthly servicing, no reliable in-product workaround exists; there is no feature to disable. As compensating controls until patching completes, restrict the ability of untrusted or low-privileged users to run arbitrary code on affected hosts (application allow-listing such as WDAC/AppLocker, and limiting interactive/RDP logon rights), since local code execution is a prerequisite; monitor EDR telemetry for anomalous kernel-object manipulation or privilege-escalation behavior. Note the trade-off: these controls reduce the pool of attackers who can reach the flaw but do not remove the vulnerable code, so they are stopgaps, not substitutes for the update.
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Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
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External POC / Exploit Code
Leaving vuln.today