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Vulnerabilities/CVE-2026-21525Public Intelligence Dossier
Source: microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-21525ListedMEDIUM (raw)CVSS 6.2CWE-476

Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.

Published: 10 Feb 2026•Last updated: 17 Jun 2026, 03:48 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
Listed
Added10 Feb 2026
Due03 Mar 2026
RansomwareUnknown
CVSS score
6.2MEDIUM (raw)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Metric sourcesecure@microsoft.com
EPSS probability
4.8%0.048
Percentile92nd
Weakness type
CWE-476
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.

SOC priority

Immediate Attention

Actively exploited

Yes

Publicly disclosed

Unknown

Risk basis: CISA KEV exploitation signal; Microsoft or Microsoft-managed product relevance; Known exploitation signal from CISA KEV or ransomware metadata

Affected Products & Remediation

13 source-backed products
Affected products and versions (source)
  • microsoft windows 10 1607 · < 10.0.14393.8868 · NVD CPE · Source
  • microsoft windows 10 1809 · < 10.0.17763.8389 · NVD CPE · Source
  • microsoft windows 10 21h2 · < 10.0.19044.6937 · NVD CPE · Source
  • microsoft windows 10 22h2 · < 10.0.19045.6937 · NVD CPE · Source
  • microsoft windows 11 23h2 · < 10.0.22631.6649 · NVD CPE · Source
  • microsoft windows 11 24h2 · < 10.0.26100.7781 · NVD CPE · Source
  • microsoft windows 11 25h2 · < 10.0.26200.7781 · NVD CPE · Source
  • microsoft windows server 2012 · r2 · NVD CPE · Source
  • microsoft windows server 2016 · < 10.0.14393.8868 · NVD CPE · Source
  • microsoft windows server 2019 · < 10.0.17763.8389 · NVD CPE · Source
  • microsoft windows server 2022 · < 10.0.20348.4711; 23h2 < 10.0.25398.2149 · NVD CPE · Source
  • microsoft windows server 2022 23h2 · < 10.0.25398.2149 · NVD CPE · Source
  • microsoft windows server 2025 · < 10.0.26100.32313 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • CISA KEV: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Known exploitation (source facts)

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

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

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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)

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

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

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

Catalog entry
10 Feb 2026
Required action due
03 Mar 2026
Known ransomware use
Unknown

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Change History & Source Data

— No recorded material change

CNA / source
secure@microsoft.com
Record status · verification
UPDATED · Microsoft primary source linked; CISA KEV confirmed
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

4 public sources
CISA KEV CatalogAdded 2026-02-10msrc.microsoft.comSource recordnvd.nist.govSource recordvicarius.ioSource 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-2026-21525
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-21525
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-21525"| 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
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Correlated briefings

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.