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Vulnerabilities

Vulnerability · CVE-2026-20959

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

Published Jan 13, 2026 · catalog updated Jul 30, 2026 · Microsoft Microsoft SharePoint Server 2019

Last checked Nov 2, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-20959. EPSS is 7.68%. Act only if a listed version of Microsoft Microsoft SharePoint Server 2019 is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium4.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
7.68%
Remediation
Version ranges on file
Affected products
cpe microsoft/sharepoint server · vendor Microsoft Microsoft SharePoint Server 2019 16.0.0 <16.0.10417.20083

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/sharepoint server2016
  • cpe microsoft/sharepoint server2019
  • cpe microsoft/sharepoint server< 16.0.19127.20442
  • vendor Microsoft Microsoft SharePoint Server 2019 16.0.0 <16.0.10417.2008316.0.0 <16.0.10417.20083

How to fix CVE-2026-20959

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-20959. EPSS is 7.68%. Act only if a listed version of Microsoft Microsoft SharePoint Server 2019 is installed.

Which versions are affected?

Compare what you have installed with microsoft/sharepoint server 2016; microsoft/sharepoint server 2019; microsoft/sharepoint server < 16.0.19127.20442; Microsoft Microsoft SharePoint Server 2019 16.0.0 <16.0.10417.20083 16.0.0 <16.0.10417.20083. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 7.68%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Microsoft SharePoint security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 13, 2026 · EUVD

    Detected

    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.

  2. Jul 30, 2026 · EUVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-20959

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-20959

    30-day exploitation probability 7.68%

    first.org
  • EUVDVulnerability recordEUVD-2026-2101

    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.

    euvd.enisa.europa.eu
  • Monitored products — criticalVendor advisoryCVE-2026-20959

    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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 1, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Monitored products — criticalNov 2, 2026
  • FIRST EPSSNov 1, 2026
  • CVE.orgOct 29, 2026
  • EUVDOct 29, 2026