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Vulnerabilities/CVE-2026-81964Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-81964Unknown / EvaluatingImportant (raw)CVSS 5.5CWE-798

Windows Update Orchestrator Service Security Feature Bypass Vulnerability

Published: 13 Oct 2026•Last updated: 13 Oct 2026, 12:30 PM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
5.5Important (raw)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.3%0.003
Percentile22nd
Weakness type
CWE-798
No further CWE recorded
Remediation
Patch status unknown
KB5127648, KB5126655, KB5126657, KB5126646, KB5126653, KB5127646

Why It Matters

Analysis dossier

Why It Matters

Use of hard-coded credentials in Windows Update Orchestrator Service allows an authorized attacker to bypass a security feature locally.

SOC priority

Medium

Actively exploited

No

Publicly disclosed

Unknown

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

Affected Products & Remediation

20 source-backed products
Affected products and versions (source)
  • Windows 11 Version 26H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 26H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows Server 2022 · version range not provided by source · Microsoft MSRC · Source
  • Windows Server 2022 (Server Core installation) · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 21H2 for 32-bit Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 21H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 21H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 22H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 22H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 10 Version 22H2 for 32-bit Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows Server 2025 (Server Core installation) · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 25H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 25H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 23H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 23H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 24H2 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 24H2 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows Server 2025 · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 version 26H1 for x64-based Systems · version range not provided by source · Microsoft MSRC · Source
  • Windows 11 Version 26H1 for ARM64-based Systems · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBKB5127648, KB5126655, KB5126657, KB5126646, KB5126653, KB5127646

Vendor or catalog guidance (source)

  • Microsoft MSRC: Install the security update KB5127648 listed by MSRC
  • Microsoft MSRC: Install the security update KB5126655 listed by MSRC
  • Microsoft MSRC: Install the security update KB5126657 listed by MSRC
  • Microsoft MSRC: Install the security update KB5126646 listed by MSRC
  • Microsoft MSRC: Install the security update KB5126653 listed by MSRC

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)
No
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: Windows 11 Version 26H2 for ARM64-based Systems, Vendor: Microsoft); authentication-weakness (CWE-798)

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 affected authentication surfaces and compare versions with the advisory.Telemetry: Application inventory · A CWE match is not proof of local exposure. · Rule authentication-weakness

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. Review unexpected successful sign-ins and changes to privileged accounts on affected systems.Telemetry: SigninLogs · Access anomalies are relevant to authentication weaknesses. · Rule authentication-weakness

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 · Unknown
CPE
Unknown

Evidence & Provenance

3 public sources
api.msrc.microsoft.comSource recordnvd.nist.govSource recordmsrc.microsoft.comSource 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-2026-81964
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-81964
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-81964"| 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

Microsoft Security Update Guide · Limited verificationOctober 2026 Security UpdatesPublished 13 Oct 2026
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.