CVE-2025-41236: VMware VMXNET3 Adapter RCE Vulnerability

CVE-2025-41236 Overview

VMware ESXi, Workstation, and Fusion contain an integer-overflow vulnerability in the VMXNET3 virtual network adapter. A malicious actor with local administrative privileges on a virtual machine with VMXNET3 virtual network adapter may exploit this issue to execute code on the host. Non VMXNET3 virtual adapters are not affected by this issue.

Critical Impact
A successful exploitation of this vulnerability allows threat actors to execute arbitrary code on the host, potentially leading to full system compromise.

Affected Products

VMware ESXi
VMware Workstation
VMware Fusion

Discovery Timeline

2025-07-15 - CVE CVE-2025-41236 published to NVD
2025-07-15 - Last updated in NVD database

Technical Details for CVE-2025-41236

Vulnerability Analysis

The vulnerability in the VMXNET3 virtual network adapter allows for an integer overflow that can be leveraged by a local attacker to achieve code execution on the host. The issue pertains to the handling of certain oversized data packets that cause an overflow in buffer allocation, leading to a memory corruption.

Root Cause

The vulnerability is caused by improper handling and validation of buffer sizes in the VMXNET3 adapter, resulting in an integer overflow vulnerability classified under CWE-787: Out-of-Bounds Write.

Attack Vector

Exploitation requires local administrative access to the virtual machine running a VMXNET3 network adapter. From there, an attacker can manipulate network packet sizes to trigger the overflow condition.

// Example exploitation code (sanitized)
void exploit_vulnerability() {
    char buffer[256];
    // Simulate oversized packet causing overflow
    strcpy(buffer, "AAAAAAAAAAAAAAAA..."); // large input
    // Overflow logic to execute attacker-controlled operations
}

Detection Methods for CVE-2025-41236

Indicators of Compromise

Unusual network traffic patterns from VMXNET3 adapters
Unauthorized execution of commands from virtual machines
Unexpected changes in virtual machine configurations

Detection Strategies

Utilize network monitoring tools to detect abnormal traffic sizes and patterns emanating from VMXNET3 interfaces. Implement host-based intrusion detection systems to identify suspicious command executions.

Monitoring Recommendations

Regularly audit virtual machines for unauthorized configuration changes and continuously monitor network traffic for anomalies related to VMXNET3 adapters. Leverage SentinelOne's behavioral AI to detect deviations indicative of exploitation attempts.

How to Mitigate CVE-2025-41236

Immediate Actions Required

Disable VMXNET3 network adapters if not explicitly required.
Restrict administrative access to virtual machines running VMXNET3 adapters.
Apply any available security patches from VMware immediately.

Patch Information

Please refer to the official VMware advisory for CVE-2025-41236 and apply the provided patches as soon as they are available to remediate this vulnerability.

Workarounds

In environments where patching is not immediately possible, consider migrating affected virtual machines to network configurations that do not use VMXNET3 adapters.

bash

# Configuration example
# Disable VMXNET3 adapter configuration temporarily
esxcli network nic down -n vmnics<NIC_ID>