EUVD-2026-56357
GHSA-2v9v-p7ff-4536
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only exploitation requiring an authenticated low-privilege session against an MSMQ-enabled host; full C/I/A reflects SYSTEM-level privilege escalation with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows Message Queuing allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via heap-based buffer overflow in Windows Message Queuing (MSMQ) allows a locally authenticated attacker with low privileges to gain SYSTEM-level access across a wide range of Microsoft Windows desktop and server editions. The flaw, classified as CWE-122, spans from Windows Server 2012 through Windows Server 2025 and Windows 10/11 across multiple feature update channels, making it broadly relevant in enterprise environments where MSMQ is deployed. Patch is available from Microsoft via the MSRC update guide; no public exploit or CISA KEV listing has been identified at the time of analysis.
Technical ContextAI
Windows Message Queuing (MSMQ) is an optional Windows component that provides store-and-forward asynchronous message passing between applications, commonly used in enterprise middleware, BizTalk Server, and legacy distributed application architectures. CWE-122 (Heap-based Buffer Overflow) indicates the flaw resides in dynamic memory management within the MSMQ service process: attacker-controlled input is written beyond the bounds of a heap-allocated buffer, enabling corruption of adjacent heap metadata or function pointers. This class of vulnerability in a privileged Windows service is a classic local privilege escalation primitive, as the MSMQ service typically runs under a high-privilege account. The CVSS vector AV:L/AC:L/PR:L confirms the attack is local and requires only a low-privilege user account, consistent with a scenario where a standard Windows user interacts with MSMQ APIs or message objects to trigger the overflow in a service context.
RemediationAI
The primary remediation is applying the vendor-released patch via Microsoft's standard Windows Update or WSUS channels; fixed versions per EUVD-2026-56357 are: Windows Server 2012 build 6.2.9200.26279, Windows Server 2012 R2 build 6.3.9600.23337, Windows Server 2016/Windows 10 1607 build 10.0.14393.9418, Windows Server 2019/Windows 10 1809 build 10.0.17763.9115, Windows Server 2022 build 10.0.20348.5499, Windows Server 2025 build 10.0.26100.33296, Windows 11 23H2 build 10.0.22631.7517, Windows 11 24H2 build 10.0.26100.9168, Windows 11 25H2 build 10.0.26200.9168, and Windows 11 26H1 build 10.0.28000.2704. Full advisory details are available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62719. Where immediate patching is not feasible, the most effective compensating control is disabling the Windows Message Queuing service (msmq) via Services MMC or Group Policy on hosts where MSMQ functionality is not required - this eliminates the attack surface entirely but will break any applications that depend on MSMQ messaging. If MSMQ cannot be disabled, restrict local logon access to sensitive servers to only explicitly authorized administrative accounts to reduce the pool of potential attackers, though this does not eliminate the vulnerability for any account with local access.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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