EUVD-2026-43978
GHSA-c624-5cj9-56f8
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local EoP needing a low-privileged foothold (AV:L/PR:L), no user interaction, low complexity, yielding SYSTEM with full C/I/A impact on the same host (S:U).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Microsoft Printer Drivers allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in Microsoft Printer Drivers on Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 allows an authenticated local attacker to gain SYSTEM-level privileges by triggering a use-after-free memory-corruption condition. The flaw grants full confidentiality, integrity, and availability impact (C:H/I:H/A:H) once low-level local access is obtained. Reported by Microsoft with a patch available; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The vulnerability resides in the Microsoft Printer Drivers subsystem, the Windows print stack component responsible for rendering and processing print jobs and driver operations within privileged kernel/service context. The root cause is CWE-416 (Use After Free): a memory object is freed but a dangling reference is subsequently dereferenced or reused, allowing an attacker to manipulate freed memory to corrupt control data or execution flow. The CPE data identifies the affected platforms as Windows 11 Version 24H2, 25H2, and 26H1, plus Windows Server 2025 including the Server Core installation. Use-after-free flaws in privileged driver code are a classic vector for elevation of privilege because the printing service typically runs with high privileges, so corrupting its memory can yield code execution in that context.
RemediationAI
Apply the Microsoft security update for CVE-2026-49166; a vendor patch is available per the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49166, and administrators should deploy the corresponding cumulative update / KB for their specific build of Windows 11 24H2/25H2/26H1 or Windows Server 2025 (patch available per vendor advisory; the exact fixed version was not included in the input and should be read from the MSRC page). Until patching is complete, compensating controls include restricting local interactive and service logon on affected hosts to reduce who can reach the local attack surface, and - on systems that do not require printing - stopping and disabling the Print Spooler service (Set-Service -Name Spooler -StartupType Disabled; Stop-Service Spooler), with the trade-off that this breaks all local and network printing on that host. On print servers where the spooler must remain enabled, limit which users can install and manage printer drivers and monitor the print service for crashes indicative of memory corruption, accepting that this does not fully eliminate the underlying use-after-free.
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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