CVE-2025-21335Known exploitation

Local SYSTEM privilege escalation via use-after-free

Published Jan 14, 2025 · Updated Jun 9, 2026

Use-after-free in Microsoft Windows Hyper-V NT Kernel Integration VSP allows local users to gain SYSTEM privileges. Microsoft identifies the memory-lifetime error as a use-after-free in the NT Kernel Integration VSP but has not disclosed the affected function, freed object, or triggering operation. A low-privileged local account is required; successful exploitation crosses the local privilege boundary and grants full SYSTEM control.

CVSS severity7.8
High
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Microsoft Windows Hyper-V NT Kernel Integration VSP allows local users to gain SYSTEM privileges. Microsoft identifies the memory-lifetime error as a use-after-free in the NT Kernel Integration VSP but has not disclosed the affected function, freed object, or triggering operation. A low-privileged local account is required; successful exploitation crosses the local privilege boundary and grants full SYSTEM control.

The record

CVE
CVE-2025-21335
Published
Jan 14, 2025
Updated
Jun 9, 2026
Vendor
Microsoft
Product
Windows Server 2025 (Server Core installation)
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 14, 2025Exploitation reportedCISA Known Exploited Vulnerabilities catalog listing
  2. Jan 14, 2025CVE publishedPublication date reported by the CVE source.
  3. Jun 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=10.0.26100.0 <10.0.26100.2894

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.2894
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.2894
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.5371
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.1369
Microsoft · Windows 11 Version 22H3version=10.0.22631.0 <10.0.22631.4751
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.5371
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.4751
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.4751
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.2894

Published CVSS scores

7.8MicrosoftCVSS:3.1/AV:L/AC:L/PR:L/UI:N/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.

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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
Privilegesauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

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.

Reported exploitation

Technologies

Your stack

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Your stack

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