dbcve.org
Windows 10 1507Operating system · Microsoft

CVE-2025-55234

CRITICAL · 9.8 CVSS v3.1 Published 2025-09-09
Fix available
A fix is available. Upgrade to 10.0.10240.21128 / 10.0.14393.8422 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable 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
SMB Server might be susceptible to relay attacks depending on the configuration. An attacker who successfully exploited these vulnerabilities could perform relay attacks and make the users subject to elevation of privilege attacks. The SMB Server already supports mechanisms for hardening against relay attacks: SMB Server signing SMB Server Extended Protection for Authentication (EPA) Microsoft is releasing this CVE to provide customers with audit capabilities to help them to assess their environment and to identify any potential device or software incompatibility issues before deploying SMB Server hardening measures that protect against relay attacks. If you have not already enabled SMB Server hardening measures, we advise customers to take the following actions to be protected from these relay attacks: Assess your environment by utilizing the audit capabilities that we are exposing in the September 2025 security updates. See Support for Audit Events to deploy SMB Server Hardening—SMB Server Signing & SMB Server EPA. Adopt appropriate SMB Server hardening measures.

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 · high confidence

SMB Server contains a vulnerability that could allow relay attacks when SMB signing and Extended Protection for Authentication (EPA) are not enabled. An attacker who successfully exploits this could perform relay attacks leading to elevation of privilege.

MitigationEnable SMB Server signing and Extended Protection for Authentication (EPA) using the audit capabilities in the September 2025 security updates to harden against relay attacks.

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 1507Operating system
Affected:< 10.0.10240.21128
Windows 10 1607Operating system
Affected:< 10.0.14393.8422
Windows 10 1809Operating system
Affected:< 10.0.17763.7792
Windows 10 21h2Operating system
Affected:< 10.0.19044.6332
Windows 10 22h2Operating system
Affected:< 10.0.19045.6332
Windows 11 22h2Operating system
Affected:< 10.0.22621.5909
Windows 11 23h2Operating system
Affected:< 10.0.22631.5909
Windows 11 24h2Operating system
Affected:< 10.0.26100.6508

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 against affected ranges
    Run 'winver' or check the registry key 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion' to obtain the full build number. Compare your build to the affected versions: Windows 10 1507 < 10.0.10240.21128, 1607 < 10.0.14393.8422, 1809 < 10.0.17763.7792, 21h2 < 10.0.19044.6332, 22h2 < 10.0.19045.6332; Windows 11 22h2 < 10.0.22621.5909, 23h2 < 10.0.22631.5909, 24h2 < 10.0.26100.6508
    Affected if Your Windows build number falls within any of the version ranges listed as affected
  2. Verify SMB signing is enabled on the server
    Run 'Get-SmbServerConfiguration -OutXml' in PowerShell and inspect the 'RequireSecuritySignature' value, or check the registry key 'HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\RequireSecuritySignature' (0=disabled, 1=enabled)
    Affected if RequireSecuritySignature is set to 0 or the registry value does not exist (SMB signing is disabled or not configured)
  3. Verify Extended Protection for Authentication (EPA) is enabled
    Run 'Get-SmbServerConfiguration -OutXml' in PowerShell and inspect the 'ExtendedSecurity' value, or check the registry key 'HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\ExtendedSecurity' (0=disabled, 1=enabled)
    Affected if ExtendedSecurity is set to 0 or the registry value does not exist (EPA is disabled or not configured)

You are affected if your Windows version is below the listed builds AND SMB signing or Extended Protection for Authentication are disabled on the SMB server.

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 10.0.10240.21128 / 10.0.14393.8422 / 10.0.17763.7792 or later
Fixed in 10.0.10240.2112810.0.14393.842210.0.17763.7792
Interim mitigation

Enable SMB Server signing and Extended Protection for Authentication (EPA) using the audit capabilities in the September 2025 security updates to harden against relay attacks.

Recommended fix High confidence

September 2025 security updates (Windows 10 1507: 10.0.10240.21128 | Windows 10 1607: 10.0.14393.8422 | Windows 10 1809: 10.0.17763.7792 | Windows 10 21h2: 10.0.19044.6332 | Windows 10 22h2: 10.0.19045.6332 | Windows 11 22h2: 10.0.22621.5909 | Windows 11 23h2: 10.0.22631.5909 | Windows 11 24h2: 10.0

  1. Install the September 2025 security update for your Windows version to enable SMB Server hardening audit capabilities
  2. Run the audit mode to identify devices or software that may be incompatible with SMB Server signing or EPA before enforcing the settings
  3. Review the audit logs to identify potential compatibility issues with SMB signing or Extended Protection for Authentication (EPA)
  4. Enable SMB Server signing (enforces message signing for all connections) to prevent relay attacks
  5. Enable SMB Server Extended Protection for Authentication (EPA) for additional protection against relay attacks
  6. Test the hardened configuration in a staging environment before deploying broadly
  7. Deploy the hardening settings organization-wide after confirming compatibility
Caveat Enforcing SMB signing or EPA may cause compatibility issues with older devices or software that do not support these security features; audit first before enforcement

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

Fix this in Windows 10 1507 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,950
Get the upgrade done

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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-2025-55234 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