CVE-2021-42278
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 · uneditedActive Directory Domain Services Elevation of Privilege Vulnerability
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 · low confidenceThis is an Active Directory Domain Services vulnerability allowing elevation of privilege. Attackers could exploit this to gain higher-level access within an AD environment, potentially compromising domain-admin level 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< 10.0.19041.1348all versions= r2all versions= r2< 10.0.14393.4770< 10.0.17763.2300< 10.0.20348.350< 10.0.19042.1348CVSS 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
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/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.
-
Check Windows Server versionRun 'winver' or 'systeminfo' from command prompt, or check the registry key HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion at value 'CurrentBuild' and 'DisplayVersion'Affected if The installed version falls within the affected ranges: Server 2004 < 10.0.19041.1348, Server 2008 all/r2, Server 2012 all/r2, Server 2016 < 10.0.14393.4770, Server 2019 < 10.0.17763.2300, Server 2022 < 10.0.20348.350, Server 20h2 < 10.0.19042.1348
-
Verify AD CS role is installedRun 'Get-WindowsFeature -Name AD-Certificate' in PowerShell on the domain controller or check for the 'Active Directory Certificate Services' role in Server ManagerAffected if AD CS role is installed and the server version is vulnerable per the version check above
-
Query msDS-AllowedToActOnBehalfOfOtherIdentity attributeUse PowerShell: Get-ADComputer -Filter * -Properties msDS-AllowedToActOnBehalfOfOtherIdentity | Where-Object {$_.msDS-AllowedToActOnBehalfOfOtherIdentity -ne $null} to find computer objects with this attribute populated, or use ldp.exe to view the attribute on specific computer objectsAffected if Any computer object has a non-empty msDS-AllowedToActOnBehalfOfOtherIdentity attribute, especially if set to an account with elevated privileges
-
Audit Certificate Template PermissionsOpen 'certtmpl.msc', right-click each template, go to Security tab, and review enrollment permissions. Specifically look for 'Enrollment Agent' or 'AutoEnrollment' permissions granted to non-administrative users or domain users groupAffected if Certificate templates grant enrollment agent rights or broad enrollment permissions to low-privileged users that could enable the attack
The environment is affected if the Windows Server version is within the vulnerable ranges AND AD CS is installed, particularly if the msDS-AllowedToActOnBehalfOfOtherIdentity attribute is populated on any computer objects or if certificate templates have overly permissive enrollment rights.
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 · scoped10.0.14393.477010.0.17763.230010.0.19041.1348
Apply the relevant Microsoft security updates for CVE-2021-42278, ensure proper AD security hardening, and implement least-privilege access controls.
Upgrade to Windows Server 2019 (build 10.0.17763.2300 or later), Windows Server 2022 (build 10.0.20348.350 or later), or the respective fixed build for your version as listed in Microsoft Security Update Guide
- Identify the current Windows Server version and build number by running 'winver' or 'systeminfo' in command prompt
- Determine which fixed build applies to your Windows Server version from the version list provided
- For Windows Server 2016, apply KB5007207 or later cumulative update to reach build 10.0.14393.4770
- For Windows Server 2019, apply KB5007206 or later cumulative update to reach build 10.0.17763.2300
- For Windows Server 2022, apply KB5007196 or later cumulative update to reach build 10.0.20348.350
- For Windows Server 20H2, apply KB5006746 or later cumulative update to reach build 10.0.19042.1348
- For Windows Server 2008 or 2012 (all versions), these are end-of-life; migrate to a supported Windows Server version such as 2019 or 2022
- After applying updates, verify the build number matches or exceeds the fixed version using 'winver'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-42278 — 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-2021-42278 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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