CVE-2026-27912
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 · uneditedImproper authorization in Windows Kerberos allows an authorized attacker to elevate privileges over an adjacent 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 confidenceThis is a privilege escalation vulnerability in Windows Kerberos authentication. An authorized attacker on an adjacent network can exploit improper authorization controls to elevate their privileges, likely by manipulating Kerberos ticket requests or ticket validation processes.
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 dataall versions= r2< 10.0.14393.9060< 10.0.17763.8644< 10.0.20348.5020< 10.0.25398.2274< 10.0.26100.32690CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:L/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 Server version and build numberRun 'winver' or execute 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' in Command Prompt, or use PowerShell: [System.Environment]::OSVersion.VersionAffected if The build number is less than the fixed version for your Windows Server edition (e.g., < 10.0.14393.9060 for Server 2016, < 10.0.17763.8644 for Server 2019, < 10.0.20348.5020 for Server 2022, < 10.0.25398.2274 for Server 2022 23h2, < 10.0.26100.32690 for Server 2025)
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Confirm Kerberos authentication is in useCheck if the system is joined to an Active Directory domain by running 'echo %USERDOMAIN%' or 'Get-ADDomain' in PowerShell. Verify the Key Distribution Center (KDC) service is running: 'Get-Service kdc'Affected if The system is domain-joined and Kerberos is the default authentication protocol for domain accounts
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Verify if system is a domain controllerRun 'netdom query fsmo' or check the registry key 'HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters' exists, or use PowerShell: 'Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\NTDS\Parameters" -ErrorAction SilentlyContinue'Affected if The system is configured as an Active Directory domain controller, as these are the primary targets for Kerberos ticket manipulation attacks
You are affected if your Windows Server version is within the affected range and the system uses Kerberos authentication for Active Directory domain access.
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 · scoped10.0.14393.906010.0.17763.864410.0.20348.5020
Apply Microsoft security updates for Windows Kerberos when released. Verify that Active Directory domain controllers and affected Windows systems are patched. Test Kerberos authentication functionality after applying updates.
Apply Microsoft security update KB5055527 (or latest subsequent monthly security update) to reach the fixed build versions: 10.0.14393.9060 (WS2016), 10.0.17763.8644 (WS2019), 10.0.20348.5020 (WS2022), 10.0.25398.2274 (WS2022 23h2), 10.0.26100.32690 (WS2025); for WS2012 R2 obtain ESU support
- 1. Identify the current Windows Server version by running 'winver' or 'systeminfo' on the affected server
- 2. For Windows Server 2016, apply KB5055527 (or subsequent security update) to reach version 10.0.14393.9060 or later
- 3. For Windows Server 2019, apply KB5055527 (or subsequent security update) to reach version 10.0.17763.8644 or later
- 4. For Windows Server 2022, apply KB5055527 (or subsequent security update) to reach version 10.0.20348.5020 or later
- 5. For Windows Server 2022 23h2, apply KB5055527 (or subsequent security update) to reach version 10.0.25398.2274 or later
- 6. For Windows Server 2025, apply KB5055527 (or subsequent security update) to reach version 10.0.26100.32690 or later
- 7. For Windows Server 2012 R2, enroll in the Extended Security Updates (ESU) program if not already enrolled, then apply the relevant ESU patch
- 8. After patching, verify the version matches or exceeds the fixed build number
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-27912 — 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-2026-27912 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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- Version or environment caveats, and links to real fixes
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