IRONSMITHINTEL
HIGHCVSS7.5
|
Actively Exploited
|CISA KEV|CVE-2019-1429|Auth: none — unauthenticated|Reboot: required|Manual only

KB4523205: Windows Server Security Update (November 2019)

Microsoft Internet Explorer contains a memory corruption vulnerability which can allow for remote code execution in the context of the current user.

Published Nov 12, 2019 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, 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 Use After Free (CWE-416) vulnerability in Microsoft Internet Explorer. A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer, aka 'Scripting Engine Memory Corruption Vulnerability'. This CVE ID is unique from CVE-2019-1426, CVE-2019-1427, CVE-2019-1428. Exploitation requires remote network access, higher attack complexity, no authentication required, and user interaction required.

📧

Phishing link

→

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security
●Running internet explorer: 9, 10, 11
Fixed inKB4523205, KB4524570, KB4525106, KB4525232, KB4525234, KB4525235, KB4525236, KB4525237, KB4525241, KB4525243, KB4525246 (applies to 29 product versions)
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: http://packetstormsecurity.com/files/155433/Microsoft-Internet-Explorer-Use-After-Free.html

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 CatalogKB4523205

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB4523205 — https://support.microsoft.com/help/4523205
    1
    KB4524570 — https://support.microsoft.com/help/4524570
    1
    KB4525106 — https://support.microsoft.com/help/4525106
    1
    KB4525232 — https://support.microsoft.com/help/4525232
    1
    KB4525234 — https://support.microsoft.com/help/4525234
    1
    KB4525235 — https://support.microsoft.com/help/4525235
    1
    KB4525236 — https://support.microsoft.com/help/4525236
    1
    KB4525237 — https://support.microsoft.com/help/4525237
    1
    KB4525241 — https://support.microsoft.com/help/4525241
    1
    KB4525243 — https://support.microsoft.com/help/4525243
    1
    KB4525246 — https://support.microsoft.com/help/4525246

Supersedes: KB4517389, KB4519338, KB4519974, KB4519976, KB4519998, KB4520002, KB4520004, KB4520005, KB4520007, KB4520008, KB4520011

Affected Products

    1
    Internet Explorer 10 on Windows Server 2012
    1
    Internet Explorer 11 on Windows 10 Version 1607 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 Version 1607 for x64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1709 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 Version 1709 for ARM64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1709 for x64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1803 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 Version 1803 for ARM64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1803 for x64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1809 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 Version 1809 for ARM64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1809 for x64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1903 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 Version 1903 for ARM64-based Systems
    1
    Internet Explorer 11 on Windows 10 Version 1903 for x64-based Systems
    1
    Internet Explorer 11 on Windows 10 for 32-bit Systems
    1
    Internet Explorer 11 on Windows 10 for x64-based Systems
    1
    Internet Explorer 11 on Windows 7 for 32-bit Systems Service Pack 1
    1
    Internet Explorer 11 on Windows 7 for x64-based Systems Service Pack 1
    1
    Internet Explorer 11 on Windows 8.1 for 32-bit systems
    1
    (…9 more product versions)

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 — a reboot IS required to complete the install

Microsoft Update Catalog (manual download)

1
Open https://catalog.update.microsoft.com
2
Search for KB4523205
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 KB4523205 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4523205
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4524570
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4525106
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4525232
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4525234
    1
    (…6 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB4523205','KB4524570','KB4525106','KB4525232','KB4525234','KB4525235','KB4525236','KB4525237','KB4525241','KB4525243','KB4525246') }

References

    1
    Microsoft Security Response Center: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1429
    1
    KB article: https://support.microsoft.com/help/4523205
    1
    KB article: https://support.microsoft.com/help/4524570
    1
    KB article: https://support.microsoft.com/help/4525232
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2019-1429
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1429

Discovery Credit

Resecurity Inc. @resecurity_com, Anonymous researcher working with iDefense Labs, Ivan Fratric of Google Project Zero, Clément Lecigne of Google’s Threat Analysis Group

PowerShell automationComing soon

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

References

↗ CVE-2019-1429↗ MSRC Advisory↗ NVD↗ KBKB4523205