SYSTEM privilege escalation via truncated heap allocation
Published Jan 14, 2025 · Updated Jun 9, 2026
Heap-based buffer overflow in Microsoft Windows Hyper-V NT Kernel Integration VSP allows local users to gain SYSTEM privileges. In VkiRootAdjustSecurityDescriptorForVmwp, a 16-bit length calculation wraps before allocation, while memmove copies the full attacker-controlled ACL. The published proof of concept requires Windows Sandbox with nested virtualization and turns the overflow into kernel memory access and token replacement.
Summary
What happened
Heap-based buffer overflow in Microsoft Windows Hyper-V NT Kernel Integration VSP allows local users to gain SYSTEM privileges. In VkiRootAdjustSecurityDescriptorForVmwp, a 16-bit length calculation wraps before allocation, while memmove copies the full attacker-controlled ACL. The published proof of concept requires Windows Sandbox with nested virtualization and turns the overflow into kernel memory access and token replacement.
The record
- CVE
- CVE-2025-21333
- Published
- Jan 14, 2025
- Updated
- Jun 9, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2025 (Server Core installation)
- Classifications
- CWE-122, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 14, 2025CVE publishedPublication date reported by the CVE source.
- Jun 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.26100.0 <10.0.26100.2894
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Microsoft Windows Server 2025 Hyper-V NT Kernel Integration VSP local exploitfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- CISA Known Exploited Vulnerabilities Catalog entry for CVE-2025-21333known exploited catalog
Technologies
Your stack
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Your stack
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