CVE-2026-45603

Local privilege escalation via AFD use-after-free race

Published Jun 9, 2026 · Updated Jun 9, 2026

A race condition in the Windows Ancillary Function Driver for WinSock allows local users to elevate privileges on affected Windows systems. AFD improperly synchronizes concurrent access to a shared object, allowing one execution path to use the object after another frees it. Exploitation requires low-privileged local access and winning the race, and successful exploitation grants higher system privileges.

CVSS severity7.0
High
EPSS probability0.18%
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 the Windows Ancillary Function Driver for WinSock allows local users to elevate privileges on affected Windows systems. AFD improperly synchronizes concurrent access to a shared object, allowing one execution path to use the object after another frees it. Exploitation requires low-privileged local access and winning the race, and successful exploitation grants higher system privileges.

The record

CVE
CVE-2026-45603
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-416, CWE-362, CAPEC-29, CAPEC-26, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 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 <10.0.17763.8880

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.8880
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.32995
Microsoft · Windows 11, version 25H2version=10.0.26200.0 <10.0.26200.8655
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.9234
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.8655
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.26132
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.26132
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.7417
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.9234
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.7417
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.23228
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.8880
Microsoft · Windows 11, version 26H1version=10.0.28000.0 <10.0.28000.2269
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.7219
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.9234
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.5256
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.32995
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.8880
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.23228

Published CVSS scores

7.0Microsoft CorporationCVSS:3.1/AV:L/AC:H/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.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
CAPEC-26Leveraging Race Conditions
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.

Technologies

Your stack

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Your stack

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