CVE-2026-25499: Path Traversal Flaw in Terraform Provider for Proxmox Allows Privilege Escalation

CVE-2026-25499 was published to the National Vulnerability Database on February 4, 2026, and last updated February 11, 2026. The vulnerability affects the Terraform and OpenTofu provider for Proxmox Virtual Environment—the community-maintained provider used to manage Proxmox infrastructure via infrastructure-as-code workflows. All versions of the provider prior to 0.93.1 are affected. NIST assigns a CVSS 3.1 score of 7.5 (High), while GitHub's CNA assessment under CVSS 4.0 rates it 8.7 (High). The vulnerability is classified under CWE-22 (Path Traversal) and CWE-1188 (Insecure Default Initialization of Resource).

The root cause is an insecure sudoers configuration described in the provider's documentation. The provider requires a Proxmox user account with specific elevated privileges to execute certain operations, and the documented setup instructs administrators to grant sudo access to the tee command for that account. The tee command reads from standard input and writes to a file, making it a well-known vector for privilege escalation when granted via sudo without path restriction. An attacker able to control input to the tee invocation—or who can execute commands as the Proxmox API user—can use directory traversal sequences (../) to escape the intended working directory and write to arbitrary paths on the Proxmox host filesystem.

Impact and Exploitation Scenario

Successful exploitation allows an attacker to overwrite arbitrary files on the Proxmox host with attacker-controlled content. This is functionally equivalent to root-level file write access, enabling a range of follow-on attacks: replacing system binaries, injecting authorized SSH keys, modifying /etc/passwd or /etc/sudoers, or overwriting Proxmox configuration files. In environments where the Terraform provider runs in CI/CD pipelines with stored credentials, a compromised pipeline or a leaked API token provides the initial access required to trigger the vulnerability. The NVD description explicitly notes that the flaw "can result in escaping the folder using ../, allowing any files on the system to be edited."

The vulnerability is particularly relevant for organizations using Proxmox in automated infrastructure provisioning workflows, which are increasingly common in environments that have adopted homelab-to-enterprise Proxmox deployments alongside Terraform or OpenTofu for state management. The provider is one of the primary tools for managing Proxmox resources declaratively, and its use is widespread in the self-hosted infrastructure community.

Remediation

The fix is available in terraform-provider-proxmox version 0.93.1, released by the bpg/terraform-provider-proxmox project on GitHub. Administrators should update the provider to 0.93.1 or later immediately. In addition to updating the provider binary, existing sudoers configurations on Proxmox hosts that follow the vulnerable documentation should be reviewed and restricted. The corrected approach limits the paths accessible via the sudo-granted tee invocation to the specific directories required by the provider, preventing directory traversal. Organizations that have deployed the provider using the previously documented sudoers configuration should audit their Proxmox hosts for unauthorized file modifications, particularly in /etc/sudoers.d/, /root/.ssh/, and Proxmox configuration directories under /etc/pve/.