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Windows Server 2008Operating system · Microsoft

CVE-2025-21203

MEDIUM · 6.5 CVSS v3.1 Published 2025-04-08
Fix available
A fix is available. Upgrade to 10.0.14393.7969 / 10.0.17763.7136 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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
Buffer over-read in Windows Routing and Remote Access Service (RRAS) allows an unauthorized attacker to disclose information over a network.

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 buffer over-read vulnerability in Windows Routing and Remote Access Service (RRAS) allows an unauthenticated attacker to read sensitive memory contents across the network, resulting in information disclosure. The flaw stems from improper bounds checking when RRAS processes certain network requests.

MitigationApply the latest Microsoft security updates for Windows systems with the RRAS role enabled, particularly on Windows Server deployments.

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 Server 2008Operating system
Affected:all versions= r2
Windows Server 2012Operating system
Affected:all versions= r2
Windows Server 2016Operating system
Affected:< 10.0.14393.7969
Windows Server 2019Operating system
Affected:< 10.0.17763.7136
Windows Server 2022Operating system
Affected:< 10.0.20348.3453
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.1551
Windows Server 2025Operating system
Affected:< 10.0.26100.3775

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

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. Verify RRAS is installed or enabled
    Run 'Get-WindowsFeature -Name Routing' in PowerShell (for Server 2012+) or check the RemoteAccess service via 'Get-Service RemoteAccess'. On standalone workstations, check 'Get-WindowsOptionalFeature -Online -FeatureName Routing'
    Affected if RRAS role or feature is installed/enabled on the system
  2. Confirm the Windows Server version and build number
    Run 'winver' or execute '[System.Environment]::OSVersion.Version' in PowerShell, or use 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion"' to retrieve the exact build number
    Affected if The build number falls below the safe thresholds: Server 2016 < 14393.7969, Server 2019 < 17763.7136, Server 2022 < 20348.3453, Server 2022 23h2 < 25398.1551, Server 2025 < 26100.3775, or Server 2008/2012 (all versions)
  3. Check if the security update is installed
    Run 'Get-HotFix | Where-Object {$_.Description -like "Security Update*"}' and cross-reference with the KB number associated with CVE-2025-21203, or verify via Windows Update history
    Affected if The specific security update for CVE-2025-21203 is not present in the installed updates

The system is affected if the RRAS role is enabled AND the Windows Server version/build is below the safe thresholds AND the corresponding security patch is not installed.

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 10.0.14393.7969 / 10.0.17763.7136 / 10.0.20348.3453 or later
Fixed in 10.0.14393.796910.0.17763.713610.0.20348.3453
Interim mitigation

Apply the latest Microsoft security updates for Windows systems with the RRAS role enabled, particularly on Windows Server deployments.

Recommended fix High confidence

Windows Server 2016: 10.0.14393.7969 | Server 2019: 10.0.17763.7136 | Server 2022: 10.0.20348.3453 | Server 2022 23h2: 10.0.25398.1551 | Server 2025: 10.0.26100.3775 (or migrate from EOL versions to latest supported)

  1. 1. Identify the current Windows Server version by running 'winver' or 'systeminfo' in Command Prompt
  2. 2. Determine if your Windows Server version is within the affected range: Server 2016 < 10.0.14393.7969, Server 2019 < 10.0.17763.7136, Server 2022 < 10.0.20348.3453, Server 2022 23h2 < 10.0.25398.1551, or Server 2025 < 10.0.26100.3775
  3. 3. For Windows Server 2008/2008 R2/2012/2012 R2: Plan migration to a supported Windows Server version as these releases are end-of-life and receive no further security updates
  4. 4. For affected 2016-2025 servers: Apply the security update via Windows Update, WSUS, or download from Microsoft Update Catalog
  5. 5. After patching, verify the RRAS service is functioning correctly and confirm the build version matches or exceeds the fixed thresholds
  6. 6. Restart the server if required by the update
Caveat Windows Server 2008/2008 R2/2012/2012 R2 require full OS migration as these versions are end-of-life; standard upgrade paths may not be available

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

Fix this in Windows Server 2008 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,970
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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-2025-21203 in production — separate from our analysis above.

No notes yet

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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