CVE-2022-31681: VMware Cloud Foundation DoS Vulnerability

CVE-2022-31681 Overview

CVE-2022-31681 is a null pointer dereference vulnerability [CWE-476] affecting VMware ESXi and VMware Cloud Foundation. A malicious actor with privileges within the VMX process can trigger the dereference to cause a denial of service condition on the host. The flaw requires local access and low privileges, but no user interaction. Because the impact crosses a trust boundary from the guest VMX process to the underlying hypervisor host, the scope is changed. VMware addressed the issue in advisory VMSA-2022-0025.

Critical Impact
An attacker with VMX process privileges can crash the ESXi host, disrupting all virtual machines running on that hypervisor and causing service outages across consolidated workloads.

Affected Products

VMware ESXi 7.0 (including Update 1 through Update 3e variants)
VMware Cloud Foundation 4.x (including 4.4, 4.4.1, 4.4.1.1)
Hosts running unpatched VMX process components

Discovery Timeline

2022-10-07 - CVE-2022-31681 published to the National Vulnerability Database
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-31681

Vulnerability Analysis

The vulnerability resides in the Virtual Machine Executable (VMX) process, the user-space component on ESXi that manages each running virtual machine. A null pointer dereference [CWE-476] occurs when the VMX process accesses a memory pointer that has not been initialized or has been set to null. When dereferenced, the host triggers a fault that terminates the offending process and can destabilize the hypervisor.

Because the VMX process mediates between guest virtual machines and the underlying VMkernel, a crash in this component has cascading effects. The CVSS scope is marked as changed, reflecting that exploitation in the VMX context impacts the broader ESXi host. The result is a denial of service against the hypervisor and every workload it hosts.

Root Cause

The root cause is missing validation of a pointer within the VMX process before dereferencing it. Specific code paths within VMX access memory regions without confirming the pointer is non-null. See the VMware Security Advisory VMSA-2022-0025 for vendor technical context.

Attack Vector

Exploitation requires local access with privileges already established within the VMX process. An attacker who has compromised a process running with VMX privileges can deliver crafted input to the vulnerable code path. The dereference is then triggered, terminating the VMX worker and inducing a denial of service on the host. The vulnerability does not enable code execution or information disclosure. No public proof-of-concept exploit is available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog.

The vulnerability mechanism is described in prose only because no verified code examples are published. Refer to the vendor advisory for affected build numbers and remediation packages.

Detection Methods for CVE-2022-31681

Indicators of Compromise

Unexpected termination of the vmx process associated with one or more virtual machines on an ESXi host
Core dump files generated under /var/core/ on the ESXi host following a VMX crash
VM power state transitions to poweredOff without a corresponding administrative action in vCenter audit logs

Detection Strategies

Monitor vmkernel.log and hostd.log entries for repeated VMX process failures or segmentation faults referencing null address access
Correlate VM termination events with the source identity that interacted with the guest immediately prior to the crash
Track ESXi host uptime and per-VM availability metrics to flag clusters of unexplained VMX exits

Monitoring Recommendations

Forward ESXi syslog data, including vmkwarning.log and per-VM vmware.log, to a centralized analytics platform for retention and correlation
Establish baselines for normal VMX process restart frequency and alert on deviations
Audit privilege assignments granting access to the VMX process and review them against least-privilege policy

How to Mitigate CVE-2022-31681

Immediate Actions Required

Apply the patches listed in VMware Security Advisory VMSA-2022-0025 to all ESXi 7.0 hosts and Cloud Foundation 4.x deployments
Inventory ESXi build numbers across the estate and prioritize hosts running pre-patch versions identified in the advisory
Restrict access to accounts and services that can interact with the VMX process to the minimum necessary set

Patch Information

VMware released fixed builds for ESXi 7.0 and corresponding Cloud Foundation updates as documented in VMSA-2022-0025. Administrators should consult the advisory for the exact fixed build numbers matching their deployed version and apply the updates using standard ESXi patching workflows through vSphere Lifecycle Manager or esxcli.

Workarounds

No vendor-documented workaround exists; patching is the required remediation path
Limit local privileges on ESXi hosts so that only trusted administrators can reach the VMX process context
Maintain vSphere High Availability (HA) and cluster failover capacity so workloads can recover if a host experiences a denial of service event

bash

# Example: query the installed ESXi build to compare against VMSA-2022-0025 fixed versions
esxcli system version get

# Example: stage and apply a patch from a depot bundle
esxcli software profile update -p <profile-name> -d <depot-url>