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CVE-2021-34484: Microsoft Windows User Profile Service Privilege Escalation Vulnerability

• Severity: medium (CVSS 4.6 v2.0)
• Exploited in the wild: yes — in CISA KEV since 2022-03-31
• EPSS: 21.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-08-12 · updated 2026-08-10

Description

Windows User Profile Service Elevation of Privilege Vulnerability

Affected products

• Microsoft Windows 10 Version 1507: before 10.0.10240.19022 — fixed in 10.0.10240.19022
• Microsoft Windows 10 1607: before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows 10: before 10.0.17763.2114 — fixed in 10.0.17763.2114
• Microsoft Windows 10 1909: before 10.0.18363.1734 — fixed in 10.0.18363.1734
• Microsoft Windows 10 2004: before 10.0.19041.1165 — fixed in 10.0.19041.1165
• Microsoft Windows 10 20H2: before 10.0.19042.1165 — fixed in 10.0.19042.1165
• Microsoft Windows 10 21H1: before 10.0.19043.1165 — fixed in 10.0.19043.1165
• Microsoft Windows 7: all versions
• Microsoft Windows 8.1: all versions
• Microsoft Windows RT 8.1: all versions
• Microsoft Windows Server 2004: before 10.0.19041.1165 — fixed in 10.0.19041.1165
• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows Server 2019: before 10.0.17763.2114 — fixed in 10.0.17763.2114
• Microsoft Windows Server 20H2: before 10.0.19042.1165 — fixed in 10.0.19042.1165

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 Server 2004 10.0.19041.1165; Microsoft Windows Server 2016 10.0.14393.4583; Microsoft Windows Server 2019 10.0.17763.2114; Microsoft Windows Server 20H2 10.0.19042.1165. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34484
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34484
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34484

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