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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Mar 2022. Known ransomware use
Exchange ServerApplication · Microsoft

CVE-2018-8581

HIGH · 7.4 CVSS v3.1 Published 2018-11-14
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware Remotely reachable No privileges Zero-click Patch available

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
An elevation of privilege vulnerability exists in Microsoft Exchange Server, aka "Microsoft Exchange Server Elevation of Privilege Vulnerability." This affects Microsoft Exchange Server.

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

CVE-2018-8581 is an elevation of privilege vulnerability in Microsoft Exchange Server that allows an authenticated attacker to impersonate other users, including domain administrators. The vulnerability stems from insufficient validation in the Exchange Web Services (EWS) API, enabling attackers with valid mailbox credentials to manipulate API requests and gain unauthorized access to other users' mailboxes or perform privileged actions.

MitigationApply the Microsoft security update for CVE-2018-8581 immediately. Restrict EWS API access where possible and monitor for unusual mailbox access patterns or privilege escalation attempts.

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
Exchange ServerApplication
Affected:= 2010= 2013= 2016= 2019

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

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. Identify your Exchange Server version
    Run 'Get-ExchangeServer | Select Name,AdminDisplayVersion' in Exchange Management Shell, or check the registry key 'HKLM\SOFTWARE\Microsoft\ExchangeServer\v15\Setup' for 'AdminDisplayVersion' or 'Version'
    Affected if The version shown is 14.0.0.0 (Exchange 2010), 15.0.0.0 (Exchange 2013), 15.1.0.0 (Exchange 2016), or 15.2.0.0 (Exchange 2019)
  2. Confirm EWS virtual directory is present and enabled
    Run 'Get-WebServicesVirtualDirectory -Server <ServerName>' in Exchange Management Shell, or check IIS Manager for the EWS application under Default Web Site
    Affected if The EWS virtual directory exists and is not explicitly disabled (EWS is enabled by default)
  3. Check if the security update is installed
    Run 'Get-ExchangeServer | Format-List *Build*' to get the build number and compare against Microsoft KB4488612 (Exchange 2010), KB4488613 (Exchange 2013), KB4488611 (Exchange 2016), or KB4488614 (Exchange 2019) fixed builds, or list installed Windows updates and search for these KB numbers
    Affected if The installed build number predates the security update or the corresponding KB is not listed in installed updates

You are affected if your Exchange Server version falls within the affected ranges (2010, 2013, 2016, or 2019), EWS virtual directory is accessible, and the CVE-2018-8581 security update (KB4488612-14) is not installed.

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
Patch available Apply the vendor patch
Vendor patch portal.msrc.microsoft.com →
Interim mitigation

Apply the Microsoft security update for CVE-2018-8581 immediately. Restrict EWS API access where possible and monitor for unusual mailbox access patterns or privilege escalation attempts.

Recommended fix High confidence

Latest supported Exchange Server version (2016 Cumulative Update 23 or 2019 Cumulative Update 12 as of the last supported releases; migrate to current supported versions)

  1. Identify the current Exchange Server version and build number using Get-ExchangeServer | Format-List Name,Edition,AdminDisplayVersion
  2. Determine the appropriate target version based on your current Exchange release: For Exchange 2010, upgrade directly to Exchange 2016 or 2019; For Exchange 2013, upgrade to the latest Cumulative Update for Exchange 2013 or migrate to Exchange 2016/2019
  3. Review Microsoft documentation for migration paths: https://docs.microsoft.com/exchange/plan-and-deploy/install-uninstall-migrations
  4. Plan the upgrade/migration, ensuring compatibility with existing systems and applications
  5. Apply the latest security updates for the target Exchange version after migration
  6. Verify the upgrade was successful and Exchange services are running properly
  7. Test mail flow and Exchange functionality before returning to production
Caveat Exchange 2010 to 2016/2019 migration may require Active Directory schema updates and significant testing; review Microsoft migration documentation for feature changes and requirements

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

Fix this in Exchange Server Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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Scan for this in your stack

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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-2018-8581 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