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: Ubuntu:Pro:20.04:LTS: fastnetmon, Ubuntu:Pro:24.04:LTS: fastnetmon, Ubuntu:Pro:26.04:LTS: fastnetmon

It was discovered that FastNetMon incorrectly validated prefix lengths when decoding BGP NLRI data. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-48686)

It was discovered that FastNetMon incorrectly sanitized input in the Juniper router integration plugin. An attacker could possibly use this issue to execute arbitrary commands. (CVE-2026-48687)

It was discovered that FastNetMon incorrectly handled buffer bounds checks when processing network traffic. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-48689)

It was discovered that FastNetMon incorrectly handled encoding the BGP AS_PATH attribute. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-48691)

It was discovered that FastNetMon incorrectly validated IP address input in the Juniper router integration plugin. An attacker could possibly use this issue to inject arbitrary router configuration commands. (CVE-2026-48694)