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Vulnerabilities/CVE-2026-84020Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Running
CVE-2026-84020Unknown / EvaluatingImportant (raw)CVSS 7.0CWE-416

Windows Routing and Remote Access Service (RRAS) Elevation of Privilege 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
7.0Important (raw)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.3%0.003
Percentile16th
Weakness type
CWE-416
No further CWE recorded
Remediation
Patch status unknown
KB5127648, KB5126655, KB5126657, KB5126646, KB5126653, KB5127646

Why It Matters

Analysis dossier

Why It Matters

Use after free in Windows Routing and Remote Access Service (RRAS) allows an authorized attacker to elevate privileges locally.

SOC priority

High

Actively exploited

No

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; 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); 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 · 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-2026-84020
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-84020
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-84020"| 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.