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Vulnerabilities/CVE-2026-88209Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-88209Unknown / EvaluatingImportant (raw)CVSS 4.6CWE-79

Microsoft Office SharePoint Spoofing Vulnerability

Published: 13 Oct 2026•Last updated: 13 Oct 2026, 12:30 PM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
4.6Important (raw)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.4%0.004
Percentile29th
Weakness type
CWE-79
No further CWE recorded
Remediation
Patch status unknown
KB5002927

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

Review

Actively exploited

No

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance

Affected Products & Remediation

1 source-backed product
Affected products and versions (source)
  • Microsoft SharePoint Server Subscription Edition · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBKB5002927

Vendor or catalog guidance (source)

  • Microsoft MSRC: Install the security update KB5002927 listed by MSRC

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
No
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched microsoft-enterprise (Affected product: Microsoft SharePoint Server Subscription Edition, Vendor: Microsoft); cross-site-scripting (CWE-79)

Exposure

  1. Identify affected Microsoft products and compare local builds with the MSRC advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · The MSRC product/build mapping establishes applicability. · Rule microsoft-enterprise
  2. Identify the affected web component and source-stated version range.Telemetry: Application inventory · The weakness class does not identify local deployment. · Rule cross-site-scripting

Exploitation evidence

  1. Review the advisory's documented behavior on matching hosts before selecting a hunt.Telemetry: DeviceProcessEvents · Product family alone does not justify a CVE-specific detection. · Rule microsoft-enterprise
Show more (2)

Exploitation evidence

  1. Review suspicious script-bearing requests to the affected endpoint.Telemetry: Application access logs · Requests are leads, not evidence that a user session was compromised. · Rule cross-site-scripting

Response

  1. Confirm the source-stated KB or mitigation on matching assets.Telemetry: DeviceTvmSoftwareVulnerabilities · A post-update inventory check verifies remediation. · Rule microsoft-enterprise

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
secure@microsoft.com
Record status · verification
UPDATED · Unknown
CPE
cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*

Evidence & Provenance

3 public sources
msrc.microsoft.comSource recordapi.msrc.microsoft.comSource recordnvd.nist.govSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-88209
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-88209
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-88209"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

Microsoft Security Update Guide · Limited verificationOctober 2026 Security UpdatesPublished 13 Oct 2026
SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.