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Actively exploitedKnown ransomware use

CVE-2019-1458 Microsoft Win32k Privilege Escalation Vulnerability

A privilege escalation vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka 'Win32k EoP.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 10 Jan 2022.
  • CISA lists it as known to be used in ransomware campaigns.
  • Rated High severity (CVSS 7.8, scored by CISA).
  • It has been in the catalogue for 1,761 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka 'Win32k Elevation of Privilege Vulnerability'.

Affected Versions

ProductVersions
Microsoft Windows10 for 32-bit Systems
10 for x64-based Systems
10 Version 1607 for 32-bit Systems
10 Version 1607 for x64-based Systems
7 for 32-bit Systems Service Pack 1
7 for x64-based Systems Service Pack 1
Microsoft Windows Server2016
2016 (Core installation)
2008 for 32-bit Systems Service Pack 2
2008 for 32-bit Systems Service Pack 2 (Core installation)
2008 for Itanium-Based Systems Service Pack 2
2008 for x64-based Systems Service Pack 2

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Microsoft Win32k. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 10 Jul 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2019-1458
  3. CVE record: CVE-2019-1458
  4. FIRST EPSS
  5. portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1458
  6. packetstormsecurity.com/files/156651/Microsoft-Windows-WizardOpium-Local-Privilege-Escalation.html
  7. packetstormsecurity.com/files/159569/Microsoft-Windows-Uninitialized-Variable-Local-Privilege-Escala