---
id: CVE-2026-48687
title: >-
  FastNetMon Community Edition through 1.2.9 contains an OS command injection
  vulnerability in the Juniper router integration plugin
summary: >-
  FastNetMon Community Edition through 1.2.9 contains an OS command injection
  vulnerability in the Juniper router integration plugin. The _log() function in
  src/juniper_plugin/fastnetmon_juniper.php (lines 117-118) constructs shell
  command…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-78
  - CWE-78
vendor: pavel-odintsov
product: fastnetmon
affected:
  - fastnetmon <= 1.2.9
published: '2026-05-26'
updated: '2026-07-21'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48687'
references:
  - url: 'https://github.com/pavel-odintsov/fastnetmon'
    label: cve@mitre.org
  - url: >-
      https://github.com/pavel-odintsov/fastnetmon/blob/master/src/juniper_plugin/fastnetmon_juniper.php
    label: cve@mitre.org
  - url: >-
      https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48687-juniper-cmd-injection
    label: cve@mitre.org
tags:
  - nvd
epss: 0.02652
epssPercentile: 0.85035
ingestedAt: '2026-07-22T13:03:41.015Z'
---

## Overview

FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the Juniper router integration plugin. The _log() function in src/juniper_plugin/fastnetmon_juniper.php (lines 117-118) constructs shell commands by concatenating the $msg parameter directly into exec() calls: exec("echo `date` \"- {FASTNETMON] - " . $msg . " \" >> " . $FILE_LOG_TMP). The $msg variable contains unsanitized data derived from command-line arguments argv[1] through argv[3], which represent the attack IP address, direction, and power. While FastNetMon's C++ core currently passes IP addresses via inet_ntoa() (which only produces safe dotted-decimal notation), the PHP script performs no input validation or shell escaping. If the script is invoked directly, by another orchestration system, or if future code changes pass string-sourced IPs, arbitrary commands can be injected. The correct fix is to replace exec() with file_put_contents() or use escapeshellarg() on all parameters.

## Affected

- `fastnetmon <= 1.2.9`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.