Is CVE-2021-43255 in the CISA KEV catalog?

No. CVE-2021-43255 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-43255?

CVE-2021-43255 has a CVSS v3 base score of 5.5 (MEDIUM).

What is the EPSS score for CVE-2021-43255?

CVE-2021-43255 has an EPSS score of 1.96% (78th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-43255?

Install KB5002101 for Microsoft Office 2013 RT Service Pack 1. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-43255

MEDIUMEPSS 78th pctl

5.5

CVSS v3

NVD

Description

Microsoft Office Trust Center Spoofing Vulnerability

How to fix

Remediation Available

Microsoft Office 2013 RT Service Pack 1Microsoft

Install:KB5002101

Microsoft Office 2013 Service Pack 1Microsoft

Install:KB5002101Microsoft

Microsoft Office 2016Microsoft

Install:KB4504745Microsoft

Install:KB5002033Microsoft

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

1.96%probability of exploitation in 30 days

78thpercentile

Elevated risk: more likely to be exploited than 78% of all known CVEs.

References

Patch1

portal.msrc.microsoft.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-19.