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CVE-2021-40454: Rich Text Edit Control Information Disclosure Vulnerability

• Severity: low (CVSS 2.1 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-13 · updated 2026-06-17
• Weakness: CWE-312

Description

Rich Text Edit Control Information Disclosure Vulnerability

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office: 2013-sp1, 2013_rt-sp1, 2016, 2019, 2021
• Microsoft Windows 10 Version 1607: 20h2, 21h1, 1607, 1809, 1909, 2004
• Microsoft Windows 11 version 21H2: all versions
• Microsoft Windows 8.1: all versions
• Microsoft Windows RT 8.1: all versions
• Microsoft Windows Server: 20h2, 2004
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: all versions
• Microsoft Windows Server 2019: all versions
• Microsoft Windows Server 2022: all versions
• Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office 2013 Service Pack 1: from 15.0.0 before 15.0.5389.1000 — fixed in 15.0.5389.1000
• Microsoft Office 2019 for Mac: from 16.0.0 before 16.54.21101001 — fixed in 16.54.21101001
• Microsoft Office LTSC 2021: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office LTSC for Mac 2021: from 16.0.1 before 16.54.21101001 — fixed in 16.54.21101001
• Microsoft Windows 10 Version 1507: from 10.0.0 before 10.0.10240.19086 — fixed in 10.0.10240.19086
• Microsoft Windows 10 1607: from 10.0.0 before 10.0.14393.4704 — fixed in 10.0.14393.4704
• Microsoft Windows 10: from 10.0.0 before 10.0.17763.2237 — fixed in 10.0.17763.2237
• Microsoft Windows 10 1909: from 10.0.0 before 10.0.18363.1854 — fixed in 10.0.18363.1854
• Microsoft Windows 10 2004: from 10.0.0 before 10.0.19041.1288 — fixed in 10.0.19041.1288
• Microsoft Windows 10 20H2: from 10.0.0 before 10.0.19042.1288 — fixed in 10.0.19042.1288
• Microsoft Windows 10 21H1: from 10.0.0 before 10.0.19043.1288 — fixed in 10.0.19043.1288
• Microsoft Windows 11 21H2: from 10.0.0 before 10.0.22000.258 — fixed in 10.0.22000.258
• Microsoft Windows 8.1: from 6.3.0 before 6.3.9600.20144 — fixed in 6.3.9600.20144
• Microsoft Windows Server 2012: from 6.2.0 before 6.2.9200.23490 — fixed in 6.2.9200.23490
• Microsoft Windows Server 2012 R2: from 6.3.0 before 6.3.9600.20144 — fixed in 6.3.9600.20144
• Microsoft Windows Server 2016: from 10.0.0 before 10.0.14393.4704 — fixed in 10.0.14393.4704
• Microsoft Windows Server 2019: from 10.0.0 before 10.0.17763.2237 — fixed in 10.0.17763.2237

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office 2013 Service Pack 1 15.0.5389.1000; Microsoft Office 2019 for Mac 16.54.21101001; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.54.21101001; Microsoft Windows 10 Version 1507 10.0.10240.19086; Microsoft Windows 10 1607 10.0.14393.4704; Microsoft Windows 10 10.0.17763.2237; Microsoft Windows 10 1909 10.0.18363.1854; Microsoft Windows 10 2004 10.0.19041.1288; Microsoft Windows 10 20H2 10.0.19042.1288. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40454
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40454

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