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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 Mar 2026.
Windows 10 1607Operating system · Microsoft

CVE-2026-21525

MEDIUM · 6.2 CVSS v3.1 Published 2026-02-10
Fix available
A fix is available. Upgrade to 10.0.14393.8868 / 10.0.17763.8389 or later.
See remediation →
99/100
Remediation priority · Urgent
In the wild No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

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

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A null pointer dereference vulnerability exists in Windows Remote Access Connection Manager (Rasman service) that allows a local unauthorized attacker to cause a denial of service by triggering the service to crash.

MitigationApply Microsoft security updates for Windows Remote Access Connection Manager to patch the null pointer dereference vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1607Operating system
Affected:< 10.0.14393.8868
Windows 10 1809Operating system
Affected:< 10.0.17763.8389
Windows 10 21h2Operating system
Affected:< 10.0.19044.6937
Windows 10 22h2Operating system
Affected:< 10.0.19045.6937
Windows 11 23h2Operating system
Affected:< 10.0.22631.6649
Windows 11 24h2Operating system
Affected:< 10.0.26100.7781
Windows 11 25h2Operating system
Affected:< 10.0.26200.7781
Windows Server 2012Operating system
Affected:all versions= r2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify your Windows version and build number
    Affected if The build number falls below any of these thresholds: 14393.8868 (Win10 1607), 17763.8389 (Win10 1809), 19044.6937 (Win10 21h2), 19045.6937 (Win10 22h2), 22631.6649 (Win11 23h2), 26100.7781 (Win11 24h2), 26200.7781 (Win11 25h2), or is any version of Windows Server 2012/2012 R2
  2. Verify Rasman service exists
    Run 'sc query rasman' or check Services.msc for 'Remote Access Connection Manager' service
    Affected if The Rasman service is present on the system (vulnerability requires this service to be exploitable)
  3. Check Rasman service status
    Run 'sc query rasman' and note the STATE field, or check via 'Get-Service rasman' in PowerShell
    Affected if The service is running (STATE: RUNNING). If stopped, the DoS cannot be triggered remotely though the vulnerability still exists in the binary.
  4. Identify Rasman binary version
    Locate rasman.exe (typically in C:\Windows\System32\) and check its file properties, or run 'wmic datafile where "name='C:\\Windows\\System32\\rasman.exe'" get Version'
    Affected if The binary version is older than the patched versions for your Windows build, indicating an unpatched state

You are affected if your Windows version/build falls within the affected ranges AND the Remote Access Connection Manager (Rasman) service is present on your system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.14393.8868 / 10.0.17763.8389 / 10.0.19044.6937 or later
Fixed in 10.0.14393.886810.0.17763.838910.0.19044.6937
Interim mitigation

Apply Microsoft security updates for Windows Remote Access Connection Manager to patch the null pointer dereference vulnerability.

Recommended fix High confidence

Windows 10 1607: 10.0.14393.8868 | Windows 10 1809: 10.0.17763.8389 | Windows 10 21h2: 10.0.19044.6937 | Windows 10 22h2: 10.0.19045.6937 | Windows 11 23h2: 10.0.22631.6649 | Windows 11 24h2: 10.0.26100.7781 | Windows 11 25h2: 10.0.26200.7781 | Windows Server 2012 R2: migrate to a supported Windows

  1. Open Settings > Update & Security > Windows Update
  2. Click 'Check for updates' to download and install the latest security updates
  3. After installation, restart the computer to apply the update
  4. Verify the installation by running 'winver' to confirm the build number matches or exceeds the fixed version for your Windows release
Caveat Standard Windows update process; minimal risk; Windows Server 2012 R2 requires migration to supported version as it is end-of-life

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1607 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
8.0 hours of engineering $1,420
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21525 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data