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Vulnerabilities/CVE-2026-100211Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-100211Unknown / EvaluatingCritical (raw)CVSS 8.8CWE-416

Microsoft Office Excel Remote Code Execution Vulnerability

Published: 13 Oct 2026•Last updated: 15 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
8.8Critical (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.8%0.008
Percentile56th
Weakness type
CWE-416
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.

SOC priority

High

Actively exploited

No

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

7 source-backed products
Affected products and versions (source)
  • Microsoft Office LTSC for Mac 2021 · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Office LTSC for Mac 2024 · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Office 365 for Mac · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Office LTSC 2024 for 64-bit editions · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Office LTSC 2024 for 32-bit editions · version range not provided by source · Microsoft MSRC · Source
  • Microsoft 365 Apps for Enterprise for 64-bit Systems · version range not provided by source · Microsoft MSRC · Source
  • Microsoft 365 Apps for Enterprise for 32-bit Systems · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • Microsoft MSRC: Release Notes

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 user-interaction-client (CVSS AV:N, CVSS UI:R)

Exposure

  1. Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client

Exploitation evidence

  1. Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client

Response

  1. Confirm the source-stated update on affected endpoints.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule user-interaction-client

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:365_apps:-:*:*:*:enterprise:*:x64:*, cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*, cpe:2.3:a:microsoft:microsoft_365:-:*:*:*:*:macos:*:*, cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:macos:-:*, cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*, cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*, cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:macos:-:*

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-2026-100211
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-100211
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-100211"| 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.