How severe is CVE-2026-20963?

CVE-2026-20963 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-20963 being actively exploited?

Yes. CVE-2026-20963 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-03-18, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2026-20963?

CVE-2026-20963 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20963?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2026-20963 have an EU (EUVD) identifier?

Yes. CVE-2026-20963 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2114. It is also flagged as exploited in the EUVD (since 2026-03-12).

When was CVE-2026-20963 published?

CVE-2026-20963 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2026-20963

CVE-2026-20963 is a critical-severity vulnerability in Microsoft Sharepoint Server with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-03-18). The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 31% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2026-03-18)
EU (EUVD) id: EUVD-2026-2114
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2026-03-12)
Weakness: CWE-502
Affected product: Microsoft Sharepoint Server
Published: 2026-01-13
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2026-20963?: Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-20963?: CVE-2026-20963 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-20963 being actively exploited?: Yes. CVE-2026-20963 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-03-18, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-20963?: CVE-2026-20963 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-20963?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-20963 have an EU (EUVD) identifier?: Yes. CVE-2026-20963 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2114. It is also flagged as exploited in the EUVD (since 2026-03-12).
When was CVE-2026-20963 published?: CVE-2026-20963 was published on 2026-01-13 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

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