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CVE-2026-48687

FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the...

9.8 CriticalFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.65%Up 1.5 points since May 27, 2026
90%50%10%1%

What each source reports

NVD Score used 9.8

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.

Record
CVE-2026-48687
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-78
Updated
2026-11-02
CVE List 8.1

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.

Record
CVE-2026-48687
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-78
Updated
2026-11-02
EUVDEUVD-2026-31843 8.1

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.

Record
EUVD-2026-31843
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-qx97-6jw5-h44w 9.8

FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the...

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.

Record
GHSA-qx97-6jw5-h44w
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-78
Updated
2026-11-02
OSV 8.1

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.

Record
CVE-2026-48687
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2026-48687 9.8

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.

Record
DEBIAN-CVE-2026-48687
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-48687 9.8

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.

Record
UBUNTU-CVE-2026-48687
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVUSN-8429-1 No score

fastnetmon vulnerabilities

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)

Record
USN-8429-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
fastnetmon
Debian:12
All versions, plus listed versions
1.2.4-21.2.4-2+deb12u11.2.5-11.2.5-21.2.5-2~bpo12+1
Show 9 moreShow less
1.2.6-11.2.6-1~bpo12+11.2.7-11.2.7-1~bpo12+11.2.8+git20250911-11.2.8+git20250911-21.2.8-11.2.8-1~bpo12+11.2.9-1
None known
fastnetmon
Debian:13
before 1.2.9-0+deb13u1, plus listed versions
1.2.8+git20250911-11.2.8+git20250911-21.2.8-1
1.2.9-0+deb13u1
fastnetmon
Debian:14
before 1.2.9-1, plus listed versions
1.2.8+git20250911-11.2.8+git20250911-21.2.8-1
1.2.9-1
fastnetmon
Ubuntu:Pro:20.04:LTS
before 1.1.4-1ubuntu0.1~esm1, plus listed versions
1.1.4-11.1.4-1build31.1.4-1build41.1.4-1build5
1.1.4-1ubuntu0.1~esm1
fastnetmon
Ubuntu:Pro:24.04:LTS
before 1.2.6-1ubuntu0.1~esm1, plus listed versions
1.2.5-11.2.6-11.2.6-1build11.2.6-1build21.2.6-1build31.2.6-1build4
1.2.6-1ubuntu0.1~esm1
fastnetmon
Ubuntu:25.10
All versions, plus listed versions
1.2.8-1build11.2.8-1build21.2.8+git20250911-1
None known
fastnetmon
Ubuntu:26.10
All versions, plus listed versions
1.2.8+git20250911-21.2.9-11.2.9-1build11.2.9-1build2
None known
fastnetmon
Ubuntu:Pro:26.04:LTS
before 1.2.8+git20250911-2ubuntu0.1~esm1, plus listed versions
1.2.8+git20250911-11.2.8+git20250911-1build11.2.8+git20250911-1build21.2.8+git20250911-2
1.2.8+git20250911-2ubuntu0.1~esm1
fastnetmon
Ubuntu:Pro:20.04:LTS
From an advisory covering 5 CVEs
before 1.1.4-1ubuntu0.1~esm1, plus listed versions
1.1.4-11.1.4-1build31.1.4-1build41.1.4-1build5
1.1.4-1ubuntu0.1~esm1
fastnetmon
Ubuntu:Pro:24.04:LTS
From an advisory covering 5 CVEs
before 1.2.6-1ubuntu0.1~esm1, plus listed versions
1.2.5-11.2.6-11.2.6-1build11.2.6-1build21.2.6-1build31.2.6-1build4
1.2.6-1ubuntu0.1~esm1
fastnetmon
Ubuntu:Pro:26.04:LTS
From an advisory covering 5 CVEs
before 1.2.8+git20250911-2ubuntu0.1~esm1, plus listed versions
1.2.8+git20250911-11.2.8+git20250911-1build11.2.8+git20250911-1build21.2.8+git20250911-2
1.2.8+git20250911-2ubuntu0.1~esm1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-48687 is a critical vulnerability (CVSS 9.8) in Pavel-odintsov Fastnetmon, published May 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.65%, the 76th percentile. Fixed in fastnetmon 1.2.9-0+deb13u1.

References

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