Hayden

Today we’ll examine the critical security vulnerability CVE-2025-41241 discovered in VMware vCenter and walk through the step-by-step patching process. This vulnerability can trigger Denial of Service (DoS) attacks, requiring immediate attention and remediation.

 

 

1. CVE-2025-41241 Vulnerability Overview

On July 29, 2025, Broadcom issued a security advisory for a Denial of Service (DoS) vulnerability found in VMware vCenter Server. This vulnerability is classified as VMSA-2025-0014 and can seriously impact vCenter service availability without proper patching.

Key Information:

  • CVE ID: CVE-2025-41241
  • Severity: Medium
  • CVSS Score: 4.4
  • Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H

 

 

2. Root Cause and Attack Methods

This vulnerability occurs during guest OS customization API calls in VMware vCenter. If an authenticated malicious user has vCenter authentication and permissions to perform guest OS customization API calls, they can trigger this vulnerability to create a denial-of-service condition.

Attack Prerequisites:

  • Authenticated user account in vCenter
  • Permissions for guest OS customization API calls
  • Network access capability

While this vulnerability requires high privileges and has high attack complexity, successful exploitation can severely impact vCenter service availability, making immediate patching essential.

 

 

3. Affected VMware Products and Versions

The following VMware products are affected by this vulnerability:

Product Affected Versions Patched Version
VMware vCenter Server 8.0 < 8.0 U3g 8.0 U3g
VMware vCenter Server 7.0 < 7.0 U3v 7.0 U3v
VMware Cloud Foundation 5.x, 4.5.x Latest version
VMware Telco Cloud Infrastructure Applicable versions Latest version
VMware Telco Cloud Platform Applicable versions Latest version

To check your current vCenter version, log into vSphere Client and navigate to Menu → Administration → Licensing to view product version information.

 

 

4. Patch Download and Preparation

4.1 Downloading Patch Files

Patch files are available from the Broadcom Support Portal:

vCenter 8.0 U3g:

vCenter 7.0 U3v:

4.2 Pre-Patch Requirements

Complete these essential tasks before applying patches:

  1. Create Backup: Generate vCenter Server file-based backup
  2. Take Snapshot: Create powered-off snapshot of vCenter Server VM
  3. Schedule Maintenance Window: Prepare for vCenter service interruption during patching
  4. Resolve Alarms: Address existing vCenter and ESXi alarms
  5. Check Firewall Rules: Configure firewall rules for temporary IP addresses if needed

 

 

5. Step-by-Step Patching via VAMI

5.1 Accessing VAMI Interface

  1. Navigate to https://vcenter-ip-or-fqdn:5480 in web browser
  2. Login with root account or administrator@vsphere.local SSO administrator credentials
  3. Select Update tab from left navigation menu

5.2 ISO-based Patch Installation

Offline Patching Method (Recommended):

  1. Upload ISO File
    • Upload downloaded patch ISO to datastore
    • Mount ISO to CD/DVD drive in vCenter VM settings
  2. Check for Patches
    • Select Check Updates dropdown in VAMI
    • Choose Check CD ROM option
    • System searches for available updates from mounted ISO
  3. Stage and Install Patch
    • Click Stage and Install button on discovered patch
    • Read and accept End User License Agreement
    • Choose VMware Customer Experience Improvement Program participation (optional)
  4. Pre-Update Checks
    • Click Run Pre-Update Checks link
    • Verify no known issues exist on system
  5. Complete Installation
    • Enter SSO administrator password (e.g., administrator@vsphere.local)
    • Confirm vCenter Server backup completion, then click Finish
    • Monitor patch installation progress

5.3 URL-based Patch Installation

Online Patching Method:

  1. Verify Internet Connection
    • Ensure vCenter has direct internet connectivity
  2. Check Online Patches
    • From Check Updates dropdown select
    • Check CD ROM + URL option
  3. Automatic Download and Installation
    • Patch files download directly from VMware portal
    • Remaining process identical to ISO method

 

 

6. CLI-based Patching (Advanced Users)

CLI patching is also available:

# SSH to vCenter
ssh root@vcenter-ip

# Verify patch ISO mount
df -h

# Check installed software packages
software-packages list --installed

# Install patch
software-packages install --iso --acceptEulas

 

 

7. Post-Patch Verification

After patch completion, verify success using these methods:

7.1 Version Verification

  1. Check via VAMI
    • VAMI → Summary → System Information for version details
  2. Check via vSphere Client
    • vSphere Client → Menu → Administration → Licensing
  3. Check via CLI 
    /usr/lib/vmware-vmon/vmon-cli --list | grep vcenter-server

7.2 Service Status Verification

  1. VAMI Service Status
    • VAMI → Services to confirm all services are running
  2. vSphere Client Functionality Test
    • Test virtual machine create/edit/delete operations
    • Test datastore access
    • Test host management functions

 

 

8. Troubleshooting and Rollback

8.1 Common Troubleshooting

Patch Installation Failure:

  1. Collect log bundle: VAMI → Support → Log Bundle
  2. Check disk space: Minimum 25GB free space required
  3. Monitor memory usage: Temporarily high memory usage during patching

Service Start Failure:

  1. Manually restart affected service in VAMI
  2. Attempt system reboot and retry
  3. Contact Broadcom support if needed

8.2 Rollback Procedure

If patch causes issues:

  1. Snapshot Restoration
    • Power off vCenter VM
    • Restore to pre-patch snapshot
  2. Backup Restoration

 

 

While CVE-2025-41241 has medium severity, its impact on vCenter—a critical infrastructure component—requires prompt patching. Leaving this vulnerability unpatched could result in serious operational disruption, so following this guide for safe patch application is essential.

For additional questions or technical support, contact Broadcom Support or seek assistance through VMware community resources.

 

Leave a Reply