CVE-2026-78514Network attack vector

Code execution via use-after-free

Published Sep 8, 2026 · Updated Sep 9, 2026

Use-after-free in Microsoft Office Word across affected Office releases allows remote attackers to execute code after user interaction. Microsoft has not published the named code locus or the precise lifetime-management error beyond reuse of freed memory in Word. The network vector alone is insufficient: exploitation requires user interaction, and successful code executes in the Word process context.

CVSS severity8.8
High
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Microsoft Office Word across affected Office releases allows remote attackers to execute code after user interaction. Microsoft has not published the named code locus or the precise lifetime-management error beyond reuse of freed memory in Word. The network vector alone is insufficient: exploitation requires user interaction, and successful code executes in the Word process context.

The record

CVE
CVE-2026-78514
Published
Sep 8, 2026
Updated
Sep 9, 2026
Vendor
Microsoft
Product
Microsoft Office LTSC for Mac 2024
Classifications
CWE-416, T1204
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 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=-

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office LTSC for Mac 2024version=-
Microsoft · Microsoft Office 2019version=19.0.0 <16.0.10417.20207
Microsoft · Microsoft Office LTSC for Mac 2021version=-
Microsoft · Microsoft Office 365 for Macversion=-
Microsoft · Microsoft Office LTSC 2021version=16.0.1 <16.0.14334.20906
Microsoft · Microsoft Word 2016version=16.0.1 <16.0.5569.1000
Microsoft · Microsoft Office LTSC 2024version=16.0.0 <16.0.17932.20976
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <16.0.20326.20138

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1204User Execution

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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