application guard

Threat actors are exploiting CVE-2025-21333, a critical heap-based buffer overflow vulnerability in Microsoft’s Windows Hyper-V NT Kernel Integration Virtual Service Provider (VSP), which allows local attackers to escalate privileges to the SYSTEM level. The vulnerability has a CVSS score of 7.8 and is actively exploited. It resides in the vkrnlintvsp.sys driver, which facilitates communication between the host OS and container-like virtual machines. A Proof of Concept (PoC) demonstrates exploitation through I/O ring buffer manipulation, allowing arbitrary read/write in kernel memory and SYSTEM-level privilege escalation. The PoC was developed by a group of researchers including @yarden_shafir and others. Affected systems include Windows 11 Version 23H2 and potentially Version 24H2, with specific binary hashes provided. Limitations of the PoC include the need for Windows Sandbox and potential system crashes due to overflow. Mitigation strategies involve updating systems, enabling protections like Hyper-V isolation, and monitoring for exploitation signs. Microsoft addressed this vulnerability in January 2025 Patch Tuesday updates, urging users to apply patches promptly.