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CVE-2021-34448: Microsoft Windows Scripting Engine Memory Corruption Vulnerability

• Severity: critical (CVSS 9.3 v2.0)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 40.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-07-16 · updated 2026-08-10
• Weakness: CWE-787

Description

Scripting Engine Memory Corruption Vulnerability

Affected products

• Microsoft Windows 10 Version 1507: before 10.0.10240.19003 — fixed in 10.0.10240.19003
• Microsoft Windows 10 1607: before 10.0.14393.4530 — fixed in 10.0.14393.4530
• Microsoft Windows 10: before 10.0.17763.2061 — fixed in 10.0.17763.2061
• Microsoft Windows 10 1909: before 10.0.18363.1679 — fixed in 10.0.18363.1679
• Microsoft Windows 10 2004: before 10.0.19041.1110 — fixed in 10.0.19041.1110
• Microsoft Windows 10 20H2: before 10.0.19042.1110 — fixed in 10.0.19042.1110
• Microsoft Windows 10 21H1: before 10.0.19043.1110 — fixed in 10.0.19043.1110
• Microsoft Windows 7: all versions
• Microsoft Windows 8.1: all versions
• Microsoft Windows RT 8.1: all versions
• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.4530 — fixed in 10.0.14393.4530
• Microsoft Windows Server 2019: before 10.0.17763.2061 — fixed in 10.0.17763.2061

How to fix

Upgrade to a fixed version: Microsoft Windows 10 Version 1507 10.0.10240.19003; Microsoft Windows 10 1607 10.0.14393.4530; Microsoft Windows 10 10.0.17763.2061; Microsoft Windows 10 1909 10.0.18363.1679; Microsoft Windows 10 2004 10.0.19041.1110; Microsoft Windows 10 20H2 10.0.19042.1110; Microsoft Windows 10 21H1 10.0.19043.1110; Microsoft Windows Server 2016 10.0.14393.4530; Microsoft Windows Server 2019 10.0.17763.2061. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34448
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34448
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34448

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