CVE-2025-54109
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 · uneditedAccess of resource using incompatible type ('type confusion') in Windows Defender Firewall Service allows an authorized attacker to elevate privileges 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 confidenceA type confusion vulnerability in Windows Defender Firewall Service allows a locally authorized attacker to exploit improper type handling when the service accesses resources, potentially executing code with elevated (SYSTEM) privileges.
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< 10.0.10240.21128< 10.0.14393.8422< 10.0.17763.7792< 10.0.19044.6332< 10.0.19045.6332< 10.0.22621.5909< 10.0.22631.5909< 10.0.26100.6508CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/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 checksWork through these to decide whether this CVE applies to you.
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Check Windows version against affected rangesRun 'winver' or 'systeminfo' and note the build number. Compare to the affected version ranges: Windows 10 1507 requires build < 10240.21128, Windows 10 1607 requires build < 14393.8422, Windows 10 1809 requires build < 17763.7792, Windows 10 21h2 requires build < 19044.6332, Windows 10 22h2 requires build < 19045.6332, Windows 11 22h2 requires build < 22621.5909, Windows 11 23h2 requires build < 22631.5909, Windows 11 24h2 requires build < 26100.6508Affected if The installed Windows build number falls within any of the affected version ranges listed
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Verify Windows Defender Firewall Service is runningRun 'Get-Service mpssvc' or 'sc query mpssvc' to check the status of the Windows Defender Firewall ServiceAffected if The mpssvc service is in a Running state, making the vulnerable code path accessible
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Confirm local authenticated access existsIdentify whether any non-privileged local user accounts exist on the system using 'net user' or check if multiple users have login rightsAffected if There are local user accounts besides the administrator that could potentially exploit this vulnerability
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Check for suspicious service interactionsReview Windows Event Logs under Security and Application logs for event ID 4656 or 4663 entries referencing the mpssvc service or firewall rules being modified unexpectedlyAffected if Unexpected or unauthorized attempts to access or modify Windows Defender Firewall Service configuration are logged
The environment is affected if the installed Windows version falls within any of the listed affected build ranges AND the mpssvc service is running, allowing a locally authorized attacker to potentially escalate privileges to SYSTEM.
Generated from the published advisory. Verify against your own configuration.
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 · scoped10.0.10240.2112810.0.14393.842210.0.17763.7792
Apply the Microsoft security update for CVE-2025-54109 when released; until then, limit local user permissions and monitor for suspicious process behavior involving the Windows Defender Firewall Service.
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: 10.0.26100.6508
- Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
- Navigate to the Microsoft Security Update Guide at https://msrc.microsoft.com/update-guide
- Search for CVE-2025-54109 to locate the specific KB patch for your Windows version
- Apply the relevant monthly security update (typically released on Patch Tuesday) that includes the fix for this vulnerability
- Alternatively, enable Windows Update and check for updates to receive the security patch automatically
- Verify the patch was installed successfully by checking the installed updates list or running 'systeminfo' to confirm the OS build number matches or exceeds the fixed version for your release
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,168.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-54109 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-54109 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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