CVE-2026-55025

Code execution via type-confused resource access

Published Jul 14, 2026 · Updated Jul 14, 2026

Type confusion in Microsoft Office Excel allows remote attackers to execute code locally after a user opens a crafted file. Excel accesses a resource using an incompatible type, but Microsoft has not disclosed the affected parser, object, or unsafe operation. Exploitation requires user interaction and can run attacker-controlled code in the user's security context on affected Windows and macOS clients or through Office Online Server document processing.

CVSS severity7.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in Microsoft Office Excel allows remote attackers to execute code locally after a user opens a crafted file. Excel accesses a resource using an incompatible type, but Microsoft has not disclosed the affected parser, object, or unsafe operation. Exploitation requires user interaction and can run attacker-controlled code in the user's security context on affected Windows and macOS clients or through Office Online Server document processing.

The record

CVE
CVE-2026-55025
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Microsoft
Product
Microsoft Office LTSC for Mac 2024
Classifications
CWE-843, T1203, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=16.0.0 <16.111.26071215

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office LTSC for Mac 2024version=16.0.0 <16.111.26071215
Microsoft · Microsoft Office 2019version=19.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Excel 2016version=16.0.0.0 <16.0.5561.1001
Microsoft · Microsoft Office LTSC for Mac 2021version=16.0.1 <16.111.26071215
Microsoft · Microsoft Office 365 for Macversion=1.0.0 <16.111.26071215
Microsoft · Microsoft Office LTSC 2021version=16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office LTSC 2024version=16.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Office Online Serverversion=16.0.0.0 <16.0.10417.20175
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

7.8MicrosoftCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1203Exploitation for Client Execution
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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