CVE-2026-20959

mediumpriority · track · 25EPSS 0.077 · 95 %ileDEEUNLRUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

7.68% (95th) EPSS

CVSS 5.4 · medium

Is it mine?

57 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-24

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedMicrosoft SharePoint Enterprise Server 2016msrc_csaf
16.0.5535.1001:Security Update:https://support.microsoft.com/help/5002828
https://support.microsoft.com/help/5002828
FixedMicrosoft SharePoint Server 2019msrc_csaf
16.0.10417.20083:Security Update:https://support.microsoft.com/help/5002825
https://support.microsoft.com/help/5002825
FixedMicrosoft SharePoint Server Subscription Editionmsrc_csaf
16.0.19127.20442:Security Update:https://support.microsoft.com/help/5002822
https://support.microsoft.com/help/5002822

cvss

Technical severity, 0–10. One row per scoring source.

5.4

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.3 · impact 2.7

v3.15.4mediumAV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:Nsecondary · FSTEC (BDU) RU

v3.14.6mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:Csecondary · ENISA EU

v3.14.6mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:Nsecondary · secure@microsoft.com USexploitability 2.1 · impact 2.5

v3.15mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

v3.14.6mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:Csecondary · NCSC-NL NL

v3.14.6mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:Csecondary · Microsoft Security Response Center US

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-79USCWE-79USCWE-79USCWE-79US

affected products (57)

Products and version ranges known to be affected.

Microsoft 365 Appsall versionscert_bundDEcpe:/a:microsoft:365_apps:-
Microsoft Excel 2016all versionscert_bundDEcpe:/a:microsoft:excel_2016:-
Microsoft Office 2013 Click-to-Run (C2R)all versionscert_bundDEcpe:/a:microsoft:office:word_viewer
Microsoft Office 2016all versionscert_bundDEcpe:/a:microsoft:office_2016:-
Microsoft Office 2019all versionscert_bundDEcpe:/a:microsoft:office_2019:-
Microsoft Office LTSC 2021all versionscert_bundDEcpe:/a:microsoft:office:ltsc_2021
Microsoft Office LTSC 2024all versionscert_bundDEcpe:/a:microsoft:office:ltsc_2024
Microsoft Office LTSC for Mac 2021all versionscert_bundDEcpe:/a:microsoft:office:ltsc_for_mac_2021
Microsoft Office LTSC for Mac 2024all versionscert_bundDEcpe:/a:microsoft:office:ltsc_for_mac_2024
Microsoft Office Online Serverall versionscert_bundDEcpe:/a:microsoft:office_online_server:-
Microsoft SharePoint Enterprise Server 2016all versionscert_bundDEcpe:/a:microsoft:sharepoint:enterprise_server_2016
Microsoft SharePoint Server 2019all versionscert_bundDEcpe:/a:microsoft:sharepoint_server_2019:-
Microsoft SharePoint Server Subscription Editionall versionscert_bundDEcpe:/a:microsoft:sharepoint:server_subscription_edition
Microsoft Word 2016all versionscert_bundDEcpe:/a:microsoft:word_2016:-
Microsoft Microsoft SharePoint Enterprise Server 201616.0.0 → 16.0.5535.1001enisa_euvdEU
Microsoft Microsoft SharePoint Server 201916.0.0 → 16.0.10417.20083enisa_euvdEU
Microsoft Microsoft SharePoint Server Subscription Edition16.0.0 → 16.0.19127.20442enisa_euvdEU
Microsoft Corp Microsoft SharePoint Enterprise Server 2016≤ 16.0.5535.1001fstec_bduRU
Microsoft Corp Microsoft SharePoint Server 2019≤ 16.0.10417.20083fstec_bduRU
Microsoft Corp Microsoft SharePoint Server Subscription Edition≤ 16.0.19127.20442fstec_bduRU

showing 20 of 57

advisories (3)

Vendor and ecosystem advisories describing this.

NCSC-2026-0010Kwetsbaarheden verholpen in Microsoft OfficeNL2026-01-13csaf · ncsc_nlNL
Microsoft heeft kwetsbaarheden verholpen in diverse Office-producten.
WID-SEC-W-2026-0081Microsoft Office Produkte: Mehrere SchwachstellenDeutsch2026-01-13csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in verschiedenen Microsoft Office Produkten und Sharepoint ausnutzen, um beliebigen Programmcode auszuführen, um Informationen offenzulegen, um falsche Informationen darzustellen, und um Sicherheitsvorkehrungen zu umgehen.
msrc_CVE-2026-20959Microsoft SharePoint Server Spoofing Vulnerability2026-01-13csaf · msrc_csafUS
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund ncsc_nl msrc_csaf NVD CVE.org MITRE

published 2026-01-13modified 2026-06-17

references (3)

External citations — patches, advisories, analysis.

scry

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