Summary
Unquoted concatenation in proxmox_pct_remote passes shell metacharacters to the Proxmox host, allowing LXC commands to execute as root on the hypervisor.
Severity
Critical — CVSS 9.9 (CVE-2026-16658).
Affected Asset
Proxmox Virtual Environment with community.proxmox Ansible collection (proxmox_pct_remote plugin).
Affected Endpoint
Pct exec via Paramiko to the Proxmox host (put_file/fetch_file correct; exec unquoted).
Prerequisites
Authenticated Ansible playbook with container access; unquoted command construction.
Steps to Reproduce
Send pct exec with metacharacters (> | ; &&) to execute on host instead of container.
Evidence
Plugin source shows quoting on put_file/fetch_file but missing on exec path; vendor advisory confirms.
Impact
Full host root compromise from unprivileged LXC container.
Root Cause
String concatenation without shell quoting in _build_pct_command().
Remediation
Update collection; quote all pct exec arguments; restrict container privileges.
Verification Steps
Confirm plugin version patched; audit playbooks; test command quoting.
References
NVD CVE-2026-16658; vendor advisory; OpenCVE.