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CVE-2021-43256

25
FAUCET Score

CVE-2021-43256 is a Remote Code Execution vulnerability affecting Microsoft Excel and other Microsoft 365 applications, allowing an attacker to execute arbitrary code. It carries a CVSS score of 7.8 (High), indicating a significant risk where user interaction is required for exploitation, but successful attacks could lead to full compromise of confidentiality, integrity, and availability. While no public exploit code is available (Metasploit, Nuclei, ExploitDB), it has garnered some community discussion and media coverage, though it is not currently listed on CISA's KEV catalog as actively exploited.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
2013CPE matchmatch criteria
cpe:2.3:a:microsoft:excel:2013:sp1:*:*:*:*:x64:*
2013CPE matchmatch criteria
cpe:2.3:a:microsoft:excel:2013:sp1:*:*:*:*:x86:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x64:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.06%
Probability of exploitation in next 30 days
EPSS Percentile
79.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0206 is in the 79th percentile among its peer group of 11,621 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (14)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Office Online ServerFixed in: 16.0.10381.20001
View patch
microsoftpatch availablevia msrc
Product: Microsoft Office 2019 for 32-bit editionsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft Office 2019 for 64-bit editionsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft 365 Apps for Enterprise for 32-bit SystemsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft 365 Apps for Enterprise for 64-bit SystemsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft Office LTSC 2021 for 64-bit editionsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft Office LTSC 2021 for 32-bit editionsFixed in: https://aka.ms/OfficeSecurityReleases
microsoftpatch availablevia msrc
Product: Microsoft Excel 2016 (32-bit edition)Fixed in: 16.0.5254.1000
View patch
microsoftpatch availablevia msrc
Product: Microsoft Excel 2016 (64-bit edition)Fixed in: 16.0.5254.1000
View patch
microsoftpatch availablevia msrc
Product: Microsoft Excel 2013 RT Service Pack 1Fixed in: 15.0.5407.1000
microsoftpatch availablevia msrc
Product: Microsoft Excel 2013 Service Pack 1 (32-bit editions)Fixed in: 15.0.5407.1000
View patch
microsoftpatch availablevia msrc
Product: Microsoft Excel 2013 Service Pack 1 (64-bit editions)Fixed in: 15.0.5407.1000
View patch
microsoftpatch availablevia msrc
Product: Microsoft Office Web Apps Server 2013 Service Pack 1Fixed in: 15.0.5407.1000
View patch

Vendor Advisories (1)

microsoft2021-Dec/CVE-2021-43256Important

Microsoft Excel Remote Code Execution Vulnerability

Dec 14, 2021

References

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2021-43256
PatchVendor Advisory