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Windows Server 2012Operating system · Microsoft

CVE-2026-33826

HIGH · 8.0 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 10.0.14393.9060 / 10.0.17763.8644 or later.
See remediation →
82/100
Remediation priority · High
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
Improper input validation in Windows Active Directory allows an authorized attacker to execute code 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 confidence

Improper input validation vulnerability in Windows Active Directory permits an authenticated attacker with adjacent network access to execute arbitrary code. The vulnerability stems from insufficient validation of input within AD components, potentially allowing specially crafted network requests to trigger code execution.

MitigationApply Microsoft security updates for Windows Active Directory when available; implement network segmentation to restrict adjacent network access; follow least-privilege principles for AD service accounts.

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 2012Operating system
Affected:= r2
Windows Server 2016Operating system
Affected:< 10.0.14393.9060
Windows Server 2019Operating system
Affected:< 10.0.17763.8644
Windows Server 2022Operating system
Affected:< 10.0.20348.5020
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.2274
Windows Server 2025Operating system
Affected:< 10.0.26100.32690

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
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 checks

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

  1. Verify if the system is running Active Directory Domain Services
    Run 'Get-WindowsFeature -Name AD-Domain-Services' in PowerShell on the target server or check Server Manager for the AD DS role
    Affected if Active Directory Domain Services role is installed and running (system is a Domain Controller)
  2. Determine the installed Windows Server version and build number
    Run 'winver' or execute 'systeminfo | findstr /C:"OS Version"' in Command Prompt to retrieve the exact build number
    Affected if Build number is lower than the fixed versions: 2012 R2 (any), 2016 < 10.0.14393.9060, 2019 < 10.0.17763.8644, 2022 < 10.0.20348.5020, 2022 23h2 < 10.0.25398.2274, 2025 < 10.0.26100.32690
  3. Determine if the Domain Controller is exposed to adjacent networks
    Review network adapter configurations and firewall rules to identify whether the Domain Controller has listening interfaces on network segments accessible from adjacent (non-trusted) networks
    Affected if Domain Controller network interfaces are reachable from adjacent network segments without proper network segmentation

A system is affected if it is a Domain Controller running a Windows Server version within the affected build ranges AND has network exposure to adjacent (non-trusted) network segments.

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 10.0.14393.9060 / 10.0.17763.8644 / 10.0.20348.5020 or later
Fixed in 10.0.14393.906010.0.17763.864410.0.20348.5020
Interim mitigation

Apply Microsoft security updates for Windows Active Directory when available; implement network segmentation to restrict adjacent network access; follow least-privilege principles for AD service accounts.

Recommended fix High confidence

Windows Server 2016: 10.0.14393.9060 | Windows Server 2019: 10.0.17763.8644 | Windows Server 2022: 10.0.20348.5020 | Windows Server 2022 23h2: 10.0.25398.2274 | Windows Server 2025: 10.0.26100.32690

  1. Check current Windows Server version by running 'winver' or 'systeminfo' in Command Prompt
  2. Identify which Windows Server version (2012 R2, 2016, 2019, 2022, 2022 23h2, or 2025) is currently deployed
  3. For Windows Server 2016: Upgrade to build 10.0.14393.9060 or later
  4. For Windows Server 2019: Upgrade to build 10.0.17763.8644 or later
  5. For Windows Server 2022: Upgrade to build 10.0.20348.5020 or later
  6. For Windows Server 2022 23h2: Upgrade to build 10.0.25398.2274 or later
  7. For Windows Server 2025: Upgrade to build 10.0.26100.32690 or later
  8. Apply the appropriate Windows security update via Windows Update, WSUS, or Microsoft Update Catalog

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

Fix this in Windows Server 2012 Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA6.0 h
42.0 hours of engineering $7,360
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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-2026-33826 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