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CVE-2021-31955: Windows Kernel Information Disclosure Vulnerability

• Severity: low (CVSS 2.1 v2.0)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 81.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-08 · updated 2026-06-17
• Weakness: CWE-497

Description

Windows Kernel Information Disclosure Vulnerability

Affected products

• Microsoft Windows 10: before 10.0.17763.1999 — fixed in 10.0.17763.1999
• Microsoft Windows 10 1909: before 10.0.18363.1621 — fixed in 10.0.18363.1621
• Microsoft Windows 10 2004: before 10.0.19041.1052 — fixed in 10.0.19041.1052
• Microsoft Windows 10 20H2: before 10.0.19042.1052 — fixed in 10.0.19042.1052
• Microsoft Windows 10 21H1: before 10.0.19043.1052 — fixed in 10.0.19043.1052
• Microsoft Windows Server 2004: before 10.0.19041.1052 — fixed in 10.0.19041.1052
• Microsoft Windows Server 2019: before 10.0.17763.1999 — fixed in 10.0.17763.1999
• Microsoft Windows Server 20H2: before 10.0.19042.1052 — fixed in 10.0.19042.1052
• Microsoft Windows 10: from 10.0.0 before 10.0.17763.1999 — fixed in 10.0.17763.1999
• Microsoft Windows 10 1909: from 10.0.0 before 10.0.18363.1621 — fixed in 10.0.18363.1621
• Microsoft Windows 10 2004: from 10.0.0 before 10.0.19041.1052 — fixed in 10.0.19041.1052
• Microsoft Windows 10 20H2: from 10.0.0 before 10.0.19042.1052 — fixed in 10.0.19042.1052
• Microsoft Windows 10 21H1: from 10.0.0 before 10.0.19043.1052 — fixed in 10.0.19043.1052
• Microsoft Windows Server 2019: from 10.0.0 before 10.0.17763.1999 — fixed in 10.0.17763.1999
• Microsoft Windows Server version 2004: from 10.0.0 before 10.0.19041.1052 — fixed in 10.0.19041.1052
• Microsoft Windows Server version 20H2: from 10.0.0 before 10.0.19042.1052 — fixed in 10.0.19042.1052

How to fix

Upgrade to a fixed version: Microsoft Windows 10 10.0.17763.1999; Microsoft Windows 10 1909 10.0.18363.1621; Microsoft Windows 10 2004 10.0.19041.1052; Microsoft Windows 10 20H2 10.0.19042.1052; Microsoft Windows 10 21H1 10.0.19043.1052; Microsoft Windows Server 2004 10.0.19041.1052; Microsoft Windows Server 2019 10.0.17763.1999; Microsoft Windows Server 20H2 10.0.19042.1052; Microsoft Windows 10 10.0.17763.1999; Microsoft Windows 10 1909 10.0.18363.1621; Microsoft Windows 10 2004 10.0.19041.1052; Microsoft Windows 10 20H2 10.0.19042.1052. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31955
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31955
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31955

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