CVE-2021-31964Network attack vector

Authenticated user deception via undisclosed mechanism

Published Jun 8, 2021 · Updated Aug 3, 2024

Spoofing in Microsoft SharePoint Foundation 2013 and SharePoint Servers 2016 and 2019 allows remote authenticated users to deceive users. Microsoft has not published the affected component or the operation that mishandles untrusted input, leaving the spoofing mechanism undisclosed. Exploitation requires a logged-in attacker and interaction by another user, and the published impact is limited to information disclosure and content alteration rather than service interruption.

CVSS severity7.6
High
EPSS probability1.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Spoofing in Microsoft SharePoint Foundation 2013 and SharePoint Servers 2016 and 2019 allows remote authenticated users to deceive users. Microsoft has not published the affected component or the operation that mishandles untrusted input, leaving the spoofing mechanism undisclosed. Exploitation requires a logged-in attacker and interaction by another user, and the published impact is limited to information disclosure and content alteration rather than service interruption.

The record

CVE
CVE-2021-31964
Published
Jun 8, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Microsoft SharePoint Foundation 2013
Classifications
Unavailable
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.0.0 <15.0.5353.1000

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft SharePoint Foundation 2013version=15.0.0 <15.0.5353.1000
Microsoft · Microsoft SharePoint Enterprise Server 2016version=16.0.0 <16.0.5173.1000
Microsoft · Microsoft SharePoint Server 2019version=16.0.0 <16.0.10375.20000

Published CVSS scores

5.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:N
7.6Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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