EUVD-2026-43970
GHSA-mcvx-hvv7-4q3h
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Race condition gives AC:H; description states network vector and unauthorized (unauthenticated) attacker so AV:N/PR:N/UI:N; privilege elevation yields full C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionNVD
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows App Store allows an unauthorized attacker to elevate privileges over a network.
AnalysisAI
Privilege elevation in the Windows App Store component affects a broad range of Microsoft Windows client and server releases (Windows 10 1607 through Windows 11 26H1, and Windows Server 2016 through 2025), where a race condition (CWE-362) lets an unauthorized attacker win a timing window to gain elevated privileges over a network. The CVSS 3.1 score is 8.1 with a network vector and no authentication (PR:N), but high attack complexity (AC:H) reflects the difficulty of reliably winning the race. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to reach and repeatedly invoke the Windows App Store / packaged-app (AppX/MSIX) operation path over the network and to reliably win a race condition (CWE-362) - the timing window is the core prerequisite, reflected as AC:H in the CVSS vector. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals are mixed. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A remote attacker repeatedly triggers concurrent Windows App Store operations against a target and races to interleave a package activation/authorization step, winning the timing window to bypass an authorization check and act with elevated privileges. Because the CVSS vector is AV:N/AC:H/PR:N/UI:N, no credentials or user interaction are needed, but the attacker must overcome the high-complexity timing requirement to succeed. … |
| Remediation | Apply the Microsoft security update for CVE-2026-42900 as the primary fix: Patch available per vendor advisory (Microsoft), documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42900 - install the corresponding monthly cumulative update for each affected Windows 10, Windows 11, and Windows Server build, as exact fixed build numbers are enumerated per OS in the MSRC entry. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all affected Windows 10 (versions 1607-26H1), Windows 11, and Windows Server (2016-2025) systems and assess network exposure. …
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Same weakness CWE-362 – Race Condition
View allSame technique Authentication Bypass
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External POC / Exploit Code
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