CVE-2025-41238 in ESXi
Summary
by MITRE • 07/15/2025
VMware ESXi, Workstation, and Fusion contain a heap-overflow vulnerability in the PVSCSI (Paravirtualized SCSI) controller that leads to an out of-bounds write. A malicious actor with local administrative privileges on a virtual machine may exploit this issue to execute code as the virtual machine's VMX process running on the host. On ESXi, the exploitation is contained within the VMX sandbox and exploitable only with configurations that are unsupported. On Workstation and Fusion, this may lead to code execution on the machine where Workstation or Fusion is installed.
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Analysis
by VulDB Data Team • 07/17/2025
This heap-overflow vulnerability in VMware's PVSCSI controller represents a critical security flaw that demonstrates the complex attack surface present in virtualized environments. The vulnerability exists within the paravirtualized SCSI controller implementation across multiple VMware products including ESXi, Workstation, and Fusion. The technical nature of the flaw involves an out-of-bounds write condition that occurs when processing certain SCSI commands through the PVSCSI interface. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which is a well-documented class of memory corruption vulnerabilities that can lead to arbitrary code execution when properly exploited. The vulnerability's presence in the PVSCSI controller is particularly concerning because this component handles I/O operations between virtual machines and storage devices, making it a critical path for data processing within the virtualization stack.
The exploitation scenario requires a malicious actor to possess local administrative privileges within a guest virtual machine, which represents a significant privilege escalation attack vector. When successfully exploited, the vulnerability allows code execution with the privileges of the VMX process running on the host system, effectively breaking the isolation boundary that virtualization platforms are designed to maintain. This creates a severe security implication where a compromised guest operating system can potentially gain access to the host system's resources and execute arbitrary code at the host level. The attack path is particularly relevant in multi-tenant environments where guest isolation is paramount for security. From an operational perspective, this vulnerability demonstrates how flaws in hypervisor components can undermine fundamental security assumptions about virtual machine isolation, as documented in various ATT&CK framework techniques related to privilege escalation and lateral movement within virtualized environments.
The impact of this vulnerability varies significantly between VMware product lines due to their different security configurations and execution models. On ESXi systems, exploitation is constrained by the VMX sandbox environment which limits the scope of potential damage to the virtual machine's execution context, though the vulnerability remains exploitable under certain unsupported configurations. This limitation reflects VMware's security architecture decisions where the hypervisor enforces additional isolation boundaries for ESXi hosts. However, in Workstation and Fusion environments, the vulnerability presents a more direct threat to the host system's integrity, as these products typically run with higher privileges on the host operating system and lack the same sandboxing mechanisms as enterprise hypervisors. The distinction between these deployment models highlights the importance of understanding the different threat landscapes and security boundaries that exist across various VMware products. Organizations running these virtualization platforms must carefully consider their security posture and the potential impact of such vulnerabilities on their overall infrastructure security. Mitigation strategies should include immediate patching of affected systems, implementation of network segmentation to limit potential exploitation vectors, and careful review of virtualization configurations to ensure that unsupported or unnecessary features are disabled. The vulnerability also underscores the need for comprehensive security testing of hypervisor components and the importance of maintaining up-to-date security patches across all virtualization infrastructure to prevent exploitation of similar memory corruption vulnerabilities.