CVE-2026-54999

Adjacent-network code execution via TCP/IP race

Published Jul 14, 2026 · Updated Jul 14, 2026

A race condition in Microsoft Windows TCP/IP allows physically proximate attackers to execute code over an adjacent network. Microsoft identifies improper synchronization of a shared resource in the TCP/IP stack, but does not disclose the specific code locus or conflicting operations. Exploitation requires adjacent-network access, needs no credentials or user interaction, and results in code execution in the vulnerable TCP/IP context.

CVSS severity8.8
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race condition in Microsoft Windows TCP/IP allows physically proximate attackers to execute code over an adjacent network. Microsoft identifies improper synchronization of a shared resource in the TCP/IP stack, but does not disclose the specific code locus or conflicting operations. Exploitation requires adjacent-network access, needs no credentials or user interaction, and results in code execution in the vulnerable TCP/IP context.

The record

CVE
CVE-2026-54999
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-362, T1210
Attack vector
adjacent
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

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 <10.0.17763.9020

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.9020
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.33158
Microsoft · Windows 11, version 25H2version=10.0.26200.0 <10.0.26200.8875
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.9339
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.8875
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.26226
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.26226
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.7548
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.9339
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.7548
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.23291
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.9020
Microsoft · Windows 11, version 26H1version=10.0.28000.0 <10.0.28000.2525
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.9339
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.5386
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.33158
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.9020
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.23291

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:A/AC:L/PR:N/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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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