Bug 2506209 (CVE-2026-16658)
| Summary: | CVE-2026-16658 community.proxmox: community.general: community.proxmox: proxmox_pct_remote shel injection via unquoted pct exec command allows | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | jmitchel, kshier, pbohmill, security-response-team, teagle |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the community.proxmox Ansible collection's
proxmox_pct_remote connection plugin. The _build_pct_command()
method constructs a pct exec command string using unquoted string
concatenation and passes it to the Proxmox host's shell via
Paramiko. Shell metacharacters in the command (such as >, |, ;, &&,
or $()) are interpreted on the host instead of inside the target
LXC container, allowing commands intended for an unprivileged
container to execute on the hypervisor host as root. This
constitutes a container-to-host trust boundary crossing. The
put_file and fetch_file methods in the same plugin correctly use
shell quoting, indicating this is an oversight on the exec path.
|
Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Deadline: | 2026-08-22 | ||
A flaw was found in the community.proxmox Ansible collection's proxmox_pct_remote connection plugin (plugins/connection/ proxmox_pct_remote.py). The _build_pct_command() method constructs the pct exec command by joining command arguments with spaces: cmd = ["/usr/sbin/pct", "exec", str(vmid), "--", cmd] return " ".join(cmd) This string is passed to Paramiko's chan.exec_command(), which executes it through the Proxmox host's shell. Shell metacharacters in the Ansible task's command (>, <, |, ;, &&, $()) are interpreted by the host shell as root instead of being passed to pct exec for execution inside the target LXC container. For example, a task "echo test > /tmp/file" results in the redirect creating the file on the host rather than inside the container. The reporter discovered this in production when an ansible.builtin.raw task writing /etc/resolv.conf silently overwrote the Proxmox host's resolver. The plugin's put_file and fetch_file methods correctly use self._shell.quote() to wrap inner commands — the fix is to apply the same pattern to the exec path. A deprecated copy of this plugin also exists in community.general since version 10.3.0. shlex is never imported in the plugin. Upstream: https://github.com/ansible-collections/community.proxmox Affected code: plugins/connection/proxmox_pct_remote.py Affected version: all versions containing proxmox_pct_remote Also in: community.general >= 10.3.0 (deprecated copy) Fixed version: (pending — reporter provides 1-line fix) Reporter: Jake Badoino (jake.badoino)