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CVE-2026-20963

Microsoft SharePoint Deserialization of Untrusted Data

9.8 CRITICALActively exploited (CISA KEV)EPSS 29.2%
  1. Published13 Jan 2026
  2. Added to CISA KEV18 Mar 2026
  3. Remediation due21 Mar 2026
Actively exploited (CISA KEV)

Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.

Added to KEV: 18 Mar 2026Federal remediation due: 21 Mar 2026

Description

Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft SharePoint Server2016 · 2019 · < 16.0.19127.20442

Remediation

Fixed in
Microsoft SharePoint Server≥ 16.0.19127.20442

References

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Frequently asked

Is CVE-2026-20963 being actively exploited?

Yes. CVE-2026-20963 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 18 Mar 2026.

How severe is CVE-2026-20963?

CVE-2026-20963 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 29.2% probability of exploitation.

Which products are affected by CVE-2026-20963?

Affected products include Microsoft SharePoint Server.

How do I fix CVE-2026-20963?

Upgrade affected software to a fixed version, for example Microsoft SharePoint Server 16.0.19127.20442 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-20963 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.