CVE-2025-34075: Vagrant Synced Folder RCE Vulnerability

CVE-2025-34075 Overview

CVE-2025-34075 has been rejected or withdrawn by its CVE Numbering Authority. This CVE was initially assigned to document an issue that allows a guest VM to modify the host's Vagrantfile via the default synced folder, potentially leading to host-side code execution.

Critical Impact

This CVE has been rejected because the reported behavior represents documented, intended functionality that does not violate a claimed security boundary. The synced folder feature in Vagrant is designed to share files between host and guest, and this behavior is explicitly documented.

Affected Products

• HashiCorp Vagrant (synced folder functionality - documented behavior, not a vulnerability)

Discovery Timeline

• 2025-07-02 - CVE-2025-34075 published to NVD
• 2025-07-16 - CVE rejected/withdrawn - Last updated in NVD database

Technical Details for CVE-2025-34075

Vulnerability Analysis

This CVE was rejected because the reported behavior is part of Vagrant's intended design. Vagrant's synced folders feature allows bidirectional file synchronization between the host machine and guest virtual machines. When a guest VM has write access to a synced folder containing the Vagrantfile, it can modify that file, which is then executed on the host during subsequent Vagrant operations.

The CVE Numbering Authority determined this does not constitute a security vulnerability because:

1. Synced folders are explicitly designed for file sharing between host and guest
2. The behavior is documented in HashiCorp's official documentation
3. Users who configure synced folders are granting the guest VM access to host files by design
4. No security boundary claim is being violated

Root Cause

The reported issue stems from the fundamental design of Vagrant's synced folder feature. By default, Vagrant syncs the project directory (containing the Vagrantfile) to /vagrant on the guest. This is intentional behavior to facilitate development workflows where code and configuration files need to be accessible from within the VM.

Users who require isolation between the guest and host should configure their synced folders appropriately or disable them entirely if bidirectional file access is not desired.

Attack Vector

While this behavior could theoretically be exploited in certain scenarios, it requires:

• A malicious or compromised guest VM
• A synced folder configuration that includes the Vagrantfile location
• Subsequent execution of Vagrant commands on the host

Since the behavior is documented and expected, users are expected to understand the security implications of synced folder configurations. The official Vagrant Synced Folders Documentation provides guidance on proper configuration.

Detection Methods for CVE-2025-34075

Indicators of Compromise

• Unexpected modifications to Vagrantfiles on the host system
• Changes to Vagrant provisioning scripts originating from guest VMs
• Anomalous shell commands executed during Vagrant operations

Detection Strategies

• Monitor file integrity of Vagrantfiles and related configuration files
• Implement version control for Vagrant configurations to track unauthorized changes
• Review synced folder configurations to ensure they follow least-privilege principles

Monitoring Recommendations

• Enable file integrity monitoring (FIM) on directories containing Vagrant configurations
• Log and audit all Vagrant command executions on development systems
• Consider using read-only synced folder mounts where bidirectional access is not required

How to Mitigate CVE-2025-34075

Immediate Actions Required

• Review your Vagrant synced folder configurations
• Consider using explicit synced folder paths that do not include the Vagrantfile location
• Use the disabled: true option to disable default synced folders if not needed

Patch Information

No patch is required as this behavior is by design. HashiCorp has documented this functionality in their official documentation. Users concerned about this behavior should follow security best practices for Vagrant configurations.

Workarounds

• Disable the default synced folder by adding config.vm.synced_folder ".", "/vagrant", disabled: true to your Vagrantfile
• Use explicit synced folder configurations that exclude sensitive configuration files
• Consider using one-way sync (rsync) where appropriate to prevent guest modifications from affecting the host
• Run Vagrant in environments where guest VM compromise risk is acceptable

# Disable default synced folder in Vagrantfile
Vagrant.configure("2") do |config|
  # Disable the default /vagrant synced folder
  config.vm.synced_folder ".", "/vagrant", disabled: true
  
  # Optionally, create a more restrictive synced folder
  # that only shares specific directories
  config.vm.synced_folder "./src", "/home/vagrant/src", 
    type: "rsync",
    rsync__exclude: ["Vagrantfile", "*.rb"]
end