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CVE-2026-45603 Microsoft CVE debrief

CVE-2026-45603 is a HIGH severity vulnerability in Windows Ancillary Function Driver for WinSock. The vulnerability is caused by a use-after-free issue, which allows an authorized attacker to elevate privileges locally. The CVSS score for this vulnerability is 7.0, with a CVSS vector of CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-11
Advisory published
2026-06-09
Advisory updated
2026-06-11

Who should care

Administrators and users of Windows operating systems, particularly those using Windows 10, Windows 11, and Windows Server, should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The vulnerability affects multiple versions of Windows, including Windows 10, Windows 11, and Windows Server. The affected versions include Windows 10 1607, Windows 10 1809, Windows 10 21H2, Windows 10 22H2, Windows 11 23H2, Windows 11 24H2, Windows 11 25H2, Windows 11 26H1, Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025.

Defensive priority

HIGH

Recommended defensive actions

  • Apply patches and updates from Microsoft as soon as possible.
  • Review and update vulnerability management processes to ensure timely patching of affected systems.
  • Monitor system logs for potential exploitation attempts.

Evidence notes

The CVE record and NVD detail pages provide additional information about the vulnerability, including affected versions and potential mitigations.

Official resources

CVE-2026-45603 was published on 2026-06-09T17:17:28.923Z and modified on 2026-06-11T18:46:15.447Z.