PT-2026-43274 · Pavel Odintsov · Fastnetmon

Published 2026-05-26 · Updated 2026-05-26 · CVE-2026-48687

NVD

CVSS v3.1

8.1

High

Base vector

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

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.

Exploit

Fix

OS Command Injection

Weakness Enumeration

CWE-78

Related Identifiers

CVE-2026-48687

Affected Products

Fastnetmon

References · 4

• 🔥 https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48687-juniper-cmd-injection · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-48687 · Security Note
• https://github.com/pavel-odintsov/fastnetmon/blob/master/src/juniper_plugin/fastnetmon_juniper.php · Note
• https://github.com/pavel-odintsov/fastnetmon · Note