CVE-2025-49666Network attack vector

Authenticated code execution via kernel heap overflow

Published Jul 8, 2025 · Updated Feb 13, 2026

Heap-based buffer overflow in Windows Kernel on affected Windows Server releases allows remote authenticated users to execute code over a network. Microsoft identifies the kernel and heap-overwrite class but has not published the affected function, packet field, or faulty bounds operation. Exploitation requires high privileges and an enabled Setup and Boot Event Collection surface; success grants code execution on the server.

CVSS severity7.2
High
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Windows Kernel on affected Windows Server releases allows remote authenticated users to execute code over a network. Microsoft identifies the kernel and heap-overwrite class but has not published the affected function, packet field, or faulty bounds operation. Exploitation requires high privileges and an enabled Setup and Boot Event Collection surface; success grants code execution on the server.

The record

CVE
CVE-2025-49666
Published
Jul 8, 2025
Updated
Feb 13, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-122, T1210
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jul 8, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=10.0.17763.0 <10.0.17763.7558

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.7558
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.4652
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.8246
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.1732
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.8246
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.7558
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.3932
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.4652

Published CVSS scores

7.2Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:H/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.

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1210Exploitation of Remote Services

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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