Windows Kernel Information Disclosure Vulnerability

cisa required action Apply updates per vendor instructions.

1. 2021-04-14 Found exploited as a 0-day (Project Zero)
2. 2021-06-08 0-day patched (Project Zero)
3. 2021-06-08 Published
4. 2021-11-03 Added to CISA KEV
5. 2021-11-17 CISA patch deadline
6. 2025-02-04 CISA SSVC: exploitation active

Added

5 y ago (2021-11-03)

Patch by

2021-11-17 (4 y ago)

Ransomware

Not known

Required action

Apply updates per vendor instructions.

Vendor, product

Microsoft, Windows

CISA name

Microsoft Windows Kernel Information Disclosure Vulnerability

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Found

2021-04-14

Patched

2021-06-08

Details

project zero tracker

Exploitation

Active, exploited in the wild

Automatable

no

Technical impact

partial

Assessed

21 mo ago (2025-02-04)

81.11% chance of exploitation in the next 30 days, higher than 99.6% of all scored CVEs (FIRST EPSS, 2026-11-08).

• Microsoft Windows 10 Version 1809
• Microsoft Windows Server 2019
• Microsoft Windows Server 2019 (Server Core installation)
• Microsoft Windows 10 Version 1909
• Microsoft Windows 10 Version 21H1
• Microsoft Windows 10 Version 2004
• Microsoft Windows Server version 2004
• Microsoft Windows 10 Version 20H2
• Microsoft Windows Server version 20H2

Weakness

• CWE-497 Exposure of Sensitive System Information to an Unauthorized Control Sphere

• portal.msrc.microsoft.com /en-US/security-guidance/advisory/CVE-2021-31955

  patch, vendor-advisory

• cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31955

  government-resource, us-government-resource

• CVE List CVE-2021-31955
• NVD CVE-2021-31955

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