CVE-2025-21397

Code execution via undisclosed use-after-free

Published Feb 11, 2025 · Updated Feb 26, 2026

A use-after-free in Microsoft Word for affected Office LTSC and Microsoft 365 Apps builds allows local users to execute code. Microsoft identifies freed-memory reuse but has not published the affected Word function or the object-lifetime operation that leaves the stale reference. Exploitation requires a user to open a crafted file; Preview Pane is not an attack vector, and successful exploitation runs code in the user's context.

CVSS severity7.8
High
EPSS probability0.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A use-after-free in Microsoft Word for affected Office LTSC and Microsoft 365 Apps builds allows local users to execute code. Microsoft identifies freed-memory reuse but has not published the affected Word function or the object-lifetime operation that leaves the stale reference. Exploitation requires a user to open a crafted file; Preview Pane is not an attack vector, and successful exploitation runs code in the user's context.

The record

CVE
CVE-2025-21397
Published
Feb 11, 2025
Updated
Feb 26, 2026
Vendor
Microsoft
Product
Microsoft Office LTSC 2021
Classifications
CWE-416, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 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=16.0.1 <https://aka.ms/OfficeSecurityReleases

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

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 · 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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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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