CVE-2025-41238: VMware ESXi PVSCSI RCE Vulnerability

CVE-2025-41238 Overview

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.

Critical Impact
This vulnerability is critical, allowing potential code execution on the host machine through a virtual machine with local admin access.

Affected Products

VMware ESXi
VMware Workstation
VMware Fusion

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to Not Available
Not Available - CVE CVE-2025-41238 assigned
Not Available - Not Available releases security patch
2025-07-15 - CVE CVE-2025-41238 published to NVD
2025-07-15 - Last updated in NVD database

Technical Details for CVE-2025-41238

Vulnerability Analysis

The vulnerability resides in the PVSCSI controller component that incorrectly manages memory buffers leading to a heap-overflow condition. This can cause an out-of-bounds write that may result in arbitrary code execution, specifically targeting the VMX process of a virtual machine.

Root Cause

The root cause is improper bounds checking in the PVSCSI controller during data processing.

Attack Vector

This vulnerability requires local administrative privileges on a virtual machine to exploit the flaw using maliciously crafted parameters.

// Example exploitation code (sanitized)
void exploit() {
    char buffer[64];
    // Malicious input exceeding buffer capacity
    strcpy(buffer, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
}

Detection Methods for CVE-2025-41238

Indicators of Compromise

Unexpected process crashes of the VMX process
Anomalous usage patterns in virtualized environments
Unusual memory usage by virtual machine processes

Detection Strategies

Utilize host-based intrusion detection systems tuned for anomalies in VMX processes. Monitor logs for indications of exploitation attempts targeting PVSCSI operations. Employ behavior-based analysis systems focusing on deviations in virtual machine process operations.

Monitoring Recommendations

Regularly review security advisories from VMware and maintain updated security baselines on virtualization hosts. Enable continuous monitoring of system logs with a focus on process deviations and memory integrity checks.

How to Mitigate CVE-2025-41238

Immediate Actions Required

Restrict administrative access to virtual machines
Monitor and audit virtual machine configurations
Update affected VMware products to secure versions as recommended by the vendor

Patch Information

Refer to VMware security advisories and support for detailed patch application instructions to resolve the vulnerabilities in affected products.

Workarounds

Implement network segmentation to isolate management interfaces and limit the exposure of virtualized infrastructures. Ensure additional logging to detect unauthorized administrative activities.

bash

# Configuration example
# Limit administrative access to specific IP addresses
iptables -A INPUT -p tcp -s 192.168.1.10 --dport 902 -j ACCEPT
iptables -A INPUT -p tcp --dport 902 -j DROP