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OpenAdvisories
High · 8.1 CVE-2026-48687 EUVD-2026-31843GHSA-qx97-6jw5-h44w

FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the Juniper router integration plugin. The _lo…

Published May 26, 2026 · Updated May 27, 2026 · Assigned by mitre

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.

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 fastnetmon 1.2.9-1 —
Debian 13 fastnetmon 1.2.9-0+deb13u1 —
Debian 12 fastnetmon No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 fastnetmon No fix yet —
Ubuntu 25.10 fastnetmon No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 26.04 LTS fastnetmon 1.2.8+git20250911-2ubuntu0.1~esm1 USN-8429-1
Ubuntu Pro 24.04 LTS fastnetmon 1.2.6-1ubuntu0.1~esm1 USN-8429-1
Ubuntu Pro 20.04 LTS fastnetmon 1.1.4-1ubuntu0.1~esm1 USN-8429-1

Advisories 1

References