What’s Vulnerable › Vulnerabilities

CVE-2021-34480: Scripting Engine Memory Corruption Vulnerability

• Severity: medium (CVSS 6.8 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 34.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-08-12 · updated 2026-08-10
• Weakness: CWE-787

Description

Scripting Engine Memory Corruption Vulnerability

Affected products

• Microsoft Windows 10 Version 1607: 20h2, 21h1, 1607, 1809, 1909, 2004
• 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: all versions
• Microsoft Windows Server 2019: all versions
• Microsoft Windows 10 Version 1507: from 10.0.10240.0 before 10.0.10240.19022 — fixed in 10.0.10240.19022
• Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.2114 — fixed in 10.0.17763.2114
• Microsoft Windows 10 1909: from 10.0.0 before 10.0.18363.1734 — fixed in 10.0.18363.1734
• Microsoft Windows 10 2004: from 10.0.0 before 10.0.19041.1165 — fixed in 10.0.19041.1165
• Microsoft Windows 10 20H2: from 10.0.0 before 10.0.19042.1165 — fixed in 10.0.19042.1165
• Microsoft Windows 10 21H1: from 10.0.0 before 10.0.19043.1165 — fixed in 10.0.19043.1165
• Microsoft Windows 7: from 6.1.0 before 6.1.7601.25685 — fixed in 6.1.7601.25685
• Microsoft Windows 7 Service Pack 1: from 6.1.0 before 6.1.7601.25685 — fixed in 6.1.7601.25685
• Microsoft Windows 8.1: from 6.3.0 before 6.3.9600.20094 — fixed in 6.3.9600.20094
• Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0 before 6.1.7601.25685 — fixed in 6.1.7601.25685
• Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.23435 — fixed in 6.2.9200.23435
• Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.20094 — fixed in 6.3.9600.20094
• Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.2114 — fixed in 10.0.17763.2114

How to fix

Upgrade to a fixed version: Microsoft Windows 10 Version 1507 10.0.10240.19022; Microsoft Windows 10 1607 10.0.14393.4583; Microsoft Windows 10 10.0.17763.2114; Microsoft Windows 10 1909 10.0.18363.1734; Microsoft Windows 10 2004 10.0.19041.1165; Microsoft Windows 10 20H2 10.0.19042.1165; Microsoft Windows 10 21H1 10.0.19043.1165; Microsoft Windows 7 6.1.7601.25685; Microsoft Windows 7 Service Pack 1 6.1.7601.25685; Microsoft Windows 8.1 6.3.9600.20094; Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.25685; Microsoft Windows Server 2012 6.2.9200.23435. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34480
• http://packetstormsecurity.com/files/164121/Internet-Explorer-JIT-Optimization-Memory-Corruption.html
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34480

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