CASCACascade Atlas

Evidence dossier

CVE-2026-20963

Microsoft SharePoint Remote Code Execution Vulnerability

75.3–90.3Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

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

State
PUBLISHED
Published
Jan 13, 2026
Updated
Apr 2, 2026
Evidence coverage
85%
CISA KEVCatalog member

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

FIRST EPSS29.43%

2026-07-18 · v2026.06.15 · percentile 98.0%

Source stateNo scored conflict

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

microsoftoriginal assertion
container

Microsoft SharePoint Remote Code Execution Vulnerability

CISA KEVoriginal assertion
observed_exploitation

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.294300000000; percentile 0.979710000000

Applicability

Cited product scope

Trace impact →
MicrosoftMicrosoft SharePoint Enterprise Server 2016
[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.5535.1001", "versionType": "custom"}]unknown
MicrosoftMicrosoft SharePoint Server 2019
[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.10417.20083", "versionType": "custom"}]unknown
MicrosoftMicrosoft SharePoint Server Subscription Edition
[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.19127.20442", "versionType": "custom"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*; end excluding 16.0.19127.20442supported

Assessments

CVSS by origin

9.8
secure@microsoft.comCVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8
microsoftCVSS 3.1 · role unknownCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.