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Vulnerabilities/CVE-2026-27929Public Intelligence Dossier
Source: microsoft · Limited verification•Last verified: •Collection Running
CVE-2026-27929Unknown / EvaluatingHIGH (raw)CVSS 7.0CWE-367

Time-of-check time-of-use (toctou) race condition in Windows LUAFV allows an authorized attacker to elevate privileges locally.

Published: 14 Apr 2026•Last updated: 15 Oct 2026, 04:47 AM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
7.0HIGH (raw)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Metric sourcesecure@microsoft.com
EPSS probability
0.2%0.002
Percentile9th
Weakness type
CWE-367
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Time-of-check time-of-use (toctou) race condition in Windows LUAFV allows an authorized attacker to elevate privileges locally.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

14 source-backed products
Affected products and versions (source)
  • microsoft windows 10 1607 · < 10.0.14393.9060 · NVD CPE · Source
  • microsoft windows 10 1809 · < 10.0.17763.8644 · NVD CPE · Source
  • microsoft windows 10 21h2 · < 10.0.19044.7184 · NVD CPE · Source
  • microsoft windows 10 22h2 · < 10.0.19045.7184 · NVD CPE · Source
  • microsoft windows 11 23h2 · < 10.0.22631.6936 · NVD CPE · Source
  • microsoft windows 11 24h2 · < 10.0.26100.8246 · NVD CPE · Source
  • microsoft windows 11 25h2 · < 10.0.26200.8246 · NVD CPE · Source
  • microsoft windows 11 26h1 · < 10.0.28000.1836 · NVD CPE · Source
  • microsoft windows server 2012 · r2 · NVD CPE · Source
  • microsoft windows server 2016 · < 10.0.14393.9060 · NVD CPE · Source
  • microsoft windows server 2019 · < 10.0.17763.8644 · NVD CPE · Source
  • microsoft windows server 2022 · < 10.0.20348.5020; 23h2 < 10.0.25398.2274 · NVD CPE · Source
  • microsoft windows server 2022 23h2 · < 10.0.25398.2274 · NVD CPE · Source
  • microsoft windows server 2025 · < 10.0.26100.32690 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched microsoft-enterprise (Affected product: microsoft windows 10 1607, Vendor: microsoft); local-privilege-escalation (CVSS AV:L, CVSS PR:L)

Exposure

  1. Identify affected Microsoft products and compare local builds with the MSRC advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · The MSRC product/build mapping establishes applicability. · Rule microsoft-enterprise
  2. Identify hosts reporting this CVE, prioritising shared or multi-user systems.Telemetry: DeviceTvmSoftwareVulnerabilities · A local, low-privilege vector matters most where untrusted users can run code. · Rule local-privilege-escalation

Exploitation evidence

  1. Review the advisory's documented behavior on matching hosts before selecting a hunt.Telemetry: DeviceProcessEvents · Product family alone does not justify a CVE-specific detection. · Rule microsoft-enterprise
Show more (2)

Exploitation evidence

  1. Look for low-privileged processes spawning SYSTEM or root-level child processes on affected hosts.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; privilege transitions are a focused starting point, not evidence of attack. · Rule local-privilege-escalation

Response

  1. Confirm the source-stated KB or mitigation on matching assets.Telemetry: DeviceTvmSoftwareVulnerabilities · A post-update inventory check verifies remediation. · Rule microsoft-enterprise

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
secure@microsoft.com
Record status · verification
UPDATED · Microsoft primary source linked
CPE
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*, cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*, cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*, cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*, cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*, cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*, cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*, cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*, cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:*, cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:*

Evidence & Provenance

2 public sources
msrc.microsoft.comSource recordnvd.nist.govSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-27929
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-27929
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-27929"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.