# CVE-2026-48687: fastnetmon: FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the Juniper router integ...

CVE-2026-48687 is fixed in fastnetmon on 1 platform, first by fastnetmon 1.2.8+git20250911-2ubuntu0.1~esm1, released May 26, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-48687
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0165
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 26, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | fastnetmon Debian 13.5 (trixie) | 1.2.9-0+deb13u1 | [DEBIAN-CVE-2026-48687](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48687.md) | Jun 24, 2026 |
| Linux | fastnetmon Debian 14 | 1.2.9-1 | [DEBIAN-CVE-2026-48687](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48687.md) | Jun 24, 2026 |
| Linux | fastnetmon Ubuntu 20.04 LTS (focal) | 1.1.4-1ubuntu0.1~esm1 | [fastnetmon 1.1.4-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-fastnetmon-1.1.4-1ubuntu0.1-esm1.md) | Jun 24, 2026 |
| Linux | fastnetmon Ubuntu 24.04.5 LTS (noble) | 1.2.6-1ubuntu0.1~esm1 | [fastnetmon 1.2.6-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-fastnetmon-1.2.6-1ubuntu0.1-esm1.md) | Jun 24, 2026 |
| Linux | fastnetmon Ubuntu 26.04.1 LTS (resolute) | 1.2.8+git20250911-2ubuntu0.1~esm1 | [fastnetmon 1.2.8+git20250911-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-fastnetmon-1.2.8-git20250911-2ubuntu0.1-esm1.md) | May 26, 2026 |

---

Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.