CASCACascade Atlas

Evidence dossier

CVE-2026-56164

Microsoft SharePoint Server Elevation of Privilege Vulnerability

Exploited in the wild (CISA KEV since Jul 14, 2026). NVD reports CVSS 3.1 9.8. Severity assessments differ within at least one CVSS version. EPSS estimates 1.0% exploit likelihood as of Oct 22, 2026.

57.9–72.6Priority evidence range
Evidence through Oct 22, 2026, 6:07 PM UTC

As of Oct 22, 2026

Normalized restatement

Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.

State
PUBLISHED
Published
Jul 14, 2026
Updated
Oct 8, 2026
Evidence coverage
80%

Evidence chronology

What was known when

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  1. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
    Field
    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    microsoft

    Record text: Microsoft SharePoint Server Elevation of Privilege Vulnerability

    Inspect raw assertion
    Field
    container
    Value
    Microsoft SharePoint Server Elevation of Privilege Vulnerability
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 1.01% probability · 62.84th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.010110000000; percentile 0.628410000000
    Original evidence ↗

Assessments differ

NVD9.8CVSS 3.1 · source date omitted
secure@microsoft.com5.3CVSS 3.1 · source date omitted

Values are shown separately by source and CVSS version.

ExploitationCatalog member

CISA KEV · catalog date Jul 14, 2026 · first observed Sep 1, 2026

Exploit likelihood1.01%

FIRST EPSS · score date Oct 22, 2026 · 62.8th percentile · first observed Oct 22, 2026

SeverityAssessments differ

NVD · CVSS 3.1 · first observed Jul 19, 2026 · values shown separately below

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusLast verified source snapshot retained

The last verified source boundary remains in force for this claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
Review source contract
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
None
Severity assessmentAssessments differ

Eligible assertions materially conflict and remain visible side by side.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Oct 22, 2026
Resolution
Resolve conflict
Affected productsSource-reported scope

The cited source assertion is retained while canonical product linkage remains open.

Revision
casca-factor-d-obligations-v1
Cutoff
Oct 22, 2026
Resolution
Resolve identity

Source comparison

Who said what

CISA KEVOriginal assertion
Exploitation cataloged

Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
CISA-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
microsoftOriginal assertion
Record text

Microsoft SharePoint Server Elevation of Privilege Vulnerability

Inspect raw assertion
Field
container
Value
Microsoft SharePoint Server Elevation of Privilege Vulnerability
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

1.01% probability · 62.84th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.010110000000; percentile 0.628410000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
3Underlying assertions
1Canonical products
3Target assertions
0Constraint assertions

Grouped from 1 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.

Identity source boundaries
  • Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

4 scope groups

microsoft · source assertedMicrosoftMicrosoft SharePoint Enterprise Server 2016Direct source scope
Affected: 16.0.0 to before 16.0.5561.1001 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.5561.1001", "versionType": "custom"}]
microsoft · source assertedMicrosoftMicrosoft SharePoint Server 2019Direct source scope
Affected: 16.0.0 to before 16.0.10417.20175 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.10417.20175", "versionType": "custom"}]
microsoft · source assertedMicrosoftMicrosoft SharePoint Server Subscription EditionDirect source scope
Affected: 16.0.0 to before 16.0.19725.20434 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "16.0.0", "lessThan": "16.0.19725.20434", "versionType": "custom"}]
NVD CPE · APPLICATIONmicrosoftsharepoint_serverVulnerable target · 3 assertions
Any version (unconstrained) (< 16.0.19725.20434); Version 2016; Version 2019Canonical identity product-77f9def9702aa8ece74aa62c4de32bc72b167cb6f10f2eff44492cf46afc2e03Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    f815ef1d-7b60-47be-9ac2-2548f99f10e4
  2. cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 16.0.19725.20434
    Match ID
    5fa63ea8-b225-4e35-a6a3-dbdecf5ac4c8
  3. cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    6122d014-5bf1-4af4-8b4d-80205ed7785e

Affected-product evidence

Accepted scope and product mapping

1 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-77f9def9702aa8ece74aa62c4de32bc72b167cb6f10f2eff44492cf46afc2e03

Source class
Nvd cpe vulnerable target
Assertions
3
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
6c93405c-d801-4180-ac22-cc9f5175a4c472ce3faf-d9e7-40cc-b604-49e65476a961e2a36cf3-66a4-47b3-beea-acaa45316f64
Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Direct cve affected
Assertions
3
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
0e08d50b-9538-4455-8986-e9e8539127883e1337c5-37bf-404b-834a-e9486bb55df5651a9384-3581-4aa7-adf9-33d5ab3d65fd

Assessments

CVSS by origin

9.8
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.3
secure@microsoft.comCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.3
microsoftCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C

Direct CVE/CNA normalized decisions

5.3Priority eligible

microsoft

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C
Validation
Valid match
Recomputed
5.3
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1

Assessments are retained side by side under closed precedence. Cascade never averages CVSS.

Evidence boundaries

  • 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; remaining scope stays source-scoped.
  • NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
  • 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.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
  • OSV aggregation and OSV-converted NVD material are not independent corroboration.
  • Red Hat facts are vendor assertions for the exact supplied products.
  • Nonmembership and not-yet-observed states are not proof of safety.