CVE & CISA-KEV Catalog

CVE-2021-42309

HIGHEPSS 87th pctl
8.8
CVSS v3
NVD

Description

Microsoft SharePoint Server Remote Code Execution Vulnerability

CWE-94Code InjectionCWE-732Incorrect Permission Assignment for Critical Resource

How to fix

Remediation Available
Microsoft SharePoint Enterprise Server 2016Microsoft
Install:KB5002055Microsoft
Microsoft SharePoint Foundation 2013 Service Pack 1Microsoft
Install:KB5002071Microsoft
Microsoft SharePoint Server 2019Microsoft
Install:KB5002054Microsoft
Microsoft SharePoint Server Subscription EditionMicrosoft
Install:KB5002045Microsoft

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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 VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

2.93%probability of exploitation in 30 days
87thpercentile

Elevated risk: more likely to be exploited than 87% of all known CVEs.

References

Third-Party Advisory1

Related Vulnerabilities

Other CWE-94 (Code Injection) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2017-9841Critical9.8100%KEVFix
CVE-2015-1635Critical9.8100%KEV-
CVE-2022-22954Critical9.8100%KEV + Ransom-
CVE-2025-49704High8.8100%KEV + RansomFix
CVE-2025-3248Critical9.8100%KEV + RansomFix
CVE-2021-22204Medium6.8100%KEVFix

Common questions

How do I fix CVE-2021-42309?

Published advisories record a fix for 4 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2021-42309 being actively exploited?

Not that we know of. CVE-2021-42309 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 87% of all scored CVEs.

How severe is CVE-2021-42309?

CVE-2021-42309 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2021-42309 affect?

Published advisories record a fix for Microsoft SharePoint Enterprise Server 2016 (Microsoft), Microsoft SharePoint Foundation 2013 Service Pack 1 (Microsoft), Microsoft SharePoint Server 2019 (Microsoft), Microsoft SharePoint Server Subscription Edition (Microsoft). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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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 2024-11-21.