#VU102617 Heap-based buffer overflow in Windows and Windows Server - CVE-2025-21333

Vulnerability identifier: #VU102617

Vulnerability risk: High

CVSSv4.0: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2025-21333

CWE-ID: CWE-122

Exploitation vector: Local

Exploit availability: Yes

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system

Vendor: Microsoft

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a boundary error in Windows Hyper-V NT Kernel Integration VSP component. A local user can trigger a heap-based buffer overflow and execute arbitrary code with SYSTEM privileges.

Note, the vulnerability is being actively exploited in the wild.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 10 21H2 10.0.19044.5247, 10 22H2 10.0.19041.3920 - 10 22H2 10.0.19045.5247, 11 22H2 10.0.22449.1000 - 11 22H2 10.0.22621.4602, 11 23H2 10.0.22631.1825 - 11 23H2 10.0.22631.4602, 11 24H2 10.0.26052.1000 - 11 24H2 10.0.26100.2894

Windows Server: 2016 10.0.14393.10 - 2016 10.0.14393.7699, 2022 23H2 10.0.25398.887 - 2022 23H2 10.0.25398.1308, 2025 10.0.26100.1742 - 2025 10.0.26100.2605

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External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21333

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.