EUVD-2026-56308
GHSA-m4p5-298m-jcjf
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only attack vector with low-privilege user account sufficient; no interaction needed; full SYSTEM compromise yields high C/I/A with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Integer overflow or wraparound in Windows Installer allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation in Windows Installer exposes virtually every supported Windows release to local elevation-of-privilege via an integer overflow (CWE-190) in the msiexec/installer subsystem. Any low-privileged local user can trigger the flaw to gain SYSTEM-level control, with full confidentiality, integrity, and availability impact confirmed by the CVSS:3.1 AV:L/PR:L/C:H/I:H/A:H vector. Microsoft has released patches across all affected product lines; no public exploit code or CISA KEV listing has been identified at the time of this analysis.
Technical ContextAI
Windows Installer (msiexec.exe and associated runtime DLLs) is the native software packaging and installation subsystem present on all Windows releases. CWE-190 (Integer Overflow or Wraparound) describes a condition where arithmetic on a numeric value wraps past its maximum representable value, producing an unexpectedly small result - commonly used to calculate buffer sizes or memory offsets. The presence of the 'Buffer Overflow' tag alongside 'Integer Overflow' strongly suggests the overflow leads to an undersized allocation that is subsequently overwritten, a classic heap or stack corruption chain. Because Windows Installer runs with elevated privileges during installation operations and is accessible by standard user accounts, a triggerable overflow in its arithmetic paths creates a reliable local privilege escalation primitive. Affected CPE scope spans Windows 10 builds from version 1607 (10.0.14393.x) through 26H1 (10.0.28000.x) and Windows Server from 2012 (6.2.9200.x) through 2025 (10.0.26100.x), as confirmed by EUVD-2026-56308.
RemediationAI
The primary remediation is applying the vendor-released patch via Windows Update or WSUS. Microsoft has published fixed builds for all affected versions: update Windows Server 2025 to 10.0.26100.33296 or later, Server 2022 to 10.0.20348.5499 or later, Server 2019 to 10.0.17763.9115 or later, Server 2016 to 10.0.14393.9418 or later, Server 2012 R2 to 6.3.9600.23337 or later, Server 2012 to 6.2.9200.26279 or later, Windows 11 23H2 to 10.0.22631.7517 or later, Windows 11 24H2/Server 2025 baseline to 10.0.26100.9168 or later, Windows 10 21H2/22H2 to 10.0.19044.7663 / 10.0.19045.7663 or later, and Windows 10 1607 to 10.0.14393.9418 or later. Consult the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-59127 for the complete patch matrix. Where immediate patching is not possible, restrict local interactive logon and Remote Desktop access to the smallest necessary set of trusted accounts, and deploy endpoint detection rules for anomalous msiexec.exe privilege transitions as a compensating control - note this does not eliminate the vulnerability but raises detection probability.
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Same weakness CWE-190 – Integer Overflow or Wraparound
View allSame technique Buffer Overflow
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External POC / Exploit Code
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