IRONSMITHINTEL
HIGHCVSS8.4
|
Actively Exploited
|CISA KEV|CVE-2020-17144|Auth: high — administrative privileges|Reboot: required|Manual only

KB4593467: Windows Server Security Update (December 2020)

Microsoft Exchange Server improperly validates cmdlet arguments which allow an attacker to perform remote code execution.

Published Dec 10, 2020 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, with administrative privileges, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2022-05-03 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Deserialization of Untrusted Data (CWE-502) vulnerability in Microsoft Exchange Server. Microsoft Exchange Remote Code Execution Vulnerability Exploitation requires remote network access, low attack complexity, an administrative account, and user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●Exchange Administrators
●Messaging Team
●IT Security
●Running exchange server: 2010
Fixed inKB4593467 (applies to 1 product version)
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2021-11-03 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2022-05-03.

How to patch

Manual download

For air-gapped servers or out-of-band deployment. Microsoft Update Catalog returns every OS-version variant of this update.

↗ Microsoft Update CatalogKB4593467

Manual remediation steps

Apply the Microsoft Security Update

Microsoft has released an official security update that fixes this vulnerability.

Required KB Update

    1
    KB4593467 — https://support.microsoft.com/help/4593467

Supersedes: KB4536989

Affected Products

    1
    Microsoft Exchange Server 2010 Service Pack 3 Update Rollup 31

Installation Methods

Windows Update (recommended)

1
Settings → Windows Update → Check for updates
2
The security update is offered if your system is in scope
3
Restart when prompted (may or may not be required for this update)

Microsoft Update Catalog (manual download)

1
Open https://catalog.update.microsoft.com
2
Search for KB4593467
3
Download the package matching your OS architecture and Windows build
4
Run the .msu installer with administrator privileges
5
Restart when prompted

WSUS / SCCM / Intune

Approve KB4593467 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://www.microsoft.com/download/details.aspx?familyid=565a516b-f84f-4aff-ba8c-1c57c378b418

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB4593467') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-17144
    1
    KB article: https://support.microsoft.com/help/4593467
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2020-17144
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-17144

Discovery Credit

zcgonvh from A-TEAM of Legendsec at Qi'anxin Group

PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ CVE-2020-17144↗ MSRC Advisory↗ NVD↗ KBKB4593467