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Vulnerabilities/CVE-2026-27927Public Intelligence Dossier
Source: microsoft · Limited verification•Last verified: •Collection Running
CVE-2026-27927Unknown / EvaluatingHIGH (raw)CVSS 7.8CWE-362

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Projected File System 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
7.8HIGH (raw)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Metric sourcesecure@microsoft.com
EPSS probability
0.2%0.002
Percentile8th
Weakness type
CWE-362
CWE-416
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Projected File System 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

11 source-backed products
Affected products and versions (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 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 1809, 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_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:*, cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*, cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*

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-2026-27927
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-27927
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-27927"| 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.