EUVD-2026-44101
GHSA-q67p-8xjr-9rwq
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Requires an existing low-privilege local account to reach the Spooler (AV:L, PR:L), no interaction, and successful heap corruption yields SYSTEM with full C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Print Spooler Components allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Print Spooler Components affects Windows 10 (1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2019/2022/2025, where a heap-based buffer overflow (CWE-122) lets an already-authenticated local user corrupt heap memory in a Spooler component and gain SYSTEM-level privileges. Exploitation requires low-privilege local access (CVSS AV:L/PR:L) with no user interaction, yielding full confidentiality, integrity, and availability impact. There is no public exploit identified at time of analysis and the CVE is not listed in CISA KEV.
Technical ContextAI
The vulnerability lives in the Windows Print Spooler subsystem (spoolsv.exe and its associated print components), a long-standing privileged service that runs as SYSTEM and has historically been a rich source of local privilege-escalation and remote code-execution bugs (e.g., the PrintNightmare family). The root cause class is CWE-122, a heap-based buffer overflow, meaning a length or bounds check on dynamically allocated (heap) memory is insufficient, allowing an attacker-controlled operation to write past the end of an allocated buffer. Because the Spooler processes print jobs and related IOCTL/RPC input while running with high privileges, corrupting its heap can be leveraged to overwrite adjacent structures and hijack execution flow within the privileged process. The affected CPE set spans client SKUs (Windows 10 1809/21H2/22H2, Windows 11 24H2/25H2/26H1) and server SKUs (Server 2019/2022/2025, including Server Core installations).
RemediationAI
Apply the Microsoft security update for CVE-2026-50499 as described in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50499 (Patch available per vendor advisory); the exact fixed KB build varies by OS SKU and must be taken from that Update Guide entry rather than a single global version number. Prioritize deployment on multi-user and server systems where low-privilege local accounts exist. As an interim compensating control, consider stopping and disabling the Print Spooler service (Stop-Service Spooler; Set-Service Spooler -StartupType Disabled) on systems that do not need printing - this eliminates the attack surface but breaks all local and network printing and, on print servers, removes print sharing, so it is only appropriate for endpoints and servers with no print role. Restricting local logon rights and minimizing the number of low-privilege interactive accounts further reduces who can reach the vulnerable local code path.
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External POC / Exploit Code
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