External risk intelligence

Rapid7 InsightConnect Sed Plugin OS Command Injection

CVE advisorySeverity: HIGH (CVSS 8.8)

CVE-2026-9155

The vulnerability exists in a plugin for an orchestration tool that typically requires authentication to access. While it operates over a network, such plugins are generally used within internal environments or restricted management planes rather than being directly exposed to the public internet by design.

OS Command Injection

Gnu Sed

4.2.2

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory describes an OS command injection vulnerability in a Rapid7 InsightConnect plugin. The issue stems from inadequate validation of user input, which could permit authenticated attackers to run unauthorized operating system commands. The primary concern is to confirm if this specific plugin is in use and if the affected functionality is exposed.

Attackers can run commands by sending bad input.
Authentication is required to trigger the issue.
Confirm relevance and exposure if this plugin is used.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by leveraging their existing authenticated access to the system. By sending a specially crafted request that includes malicious commands within the 'expression' parameter of the Sed Plugin, they can trick the plugin into executing arbitrary operating system commands. This could lead to unauthorized control over the affected Linux system.

Requires authenticated access.
Triggered via the expression parameter.
Enables arbitrary OS command execution.

Live Threat

Current exploitation, exposure, and threat context

Authenticated attackers with access to Rapid7 InsightConnect's Sed Plugin could execute arbitrary operating system commands on Linux systems due to insufficient input validation in the expression parameter. This could affect the integrity and availability of the underlying system and any data it processes or stores.

System commands may be executed.
Exposure can occur via the expression parameter.
Arbitrary command execution is possible.

Operational Fix

Recommended remediation, mitigation, and detection steps

Real-World Ownership: Given this is an OS Command Injection vulnerability in a plugin for Rapid7 InsightConnect, responsibility likely falls to the Platform Team or Automation Engineering Team that manages InsightConnect. The first practical step is to identify all deployed instances of the Sed plugin within the organization, confirm if these instances are accessible externally or process sensitive data, and then assign an accountable owner for remediation.

Platform or Automation Engineering team owns.
Verify plugin usage and exposure.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is the Rapid7 InsightConnect Sed Plugin?

It is a component for Rapid7 InsightConnect, an orchestration and automation platform. This specific plugin acts as a utility to run text stream editing operations, often used by automation workflows to process or transform data within the platform's Linux-based environment.

What does OS Command Injection mean for CVE-2026-9155?

This vulnerability falls under the CWE-78 weakness class, which happens when software fails to properly sanitize input before passing it to a system shell. In this case, the plugin allows an attacker to manipulate the 'expression' parameter to insert their own commands, forcing the underlying Linux operating system to run unauthorized instructions.

How is this vulnerability triggered?

An attacker must have valid, authenticated access to the InsightConnect system to interact with the plugin. It cannot be triggered by unauthenticated users. The attack specifically targets the 'expression' parameter; inputs that do not utilize this parameter or lack malicious command sequences will not trigger the bug.

Is my system at risk if it is not internet-facing?

Halo Surface Signal notes that while this plugin operates over a network, it is typically deployed within restricted management planes or internal environments. Because authentication is a prerequisite, systems that are not exposed to the public internet generally have a lower risk profile, though internal unauthorized access remains a concern.

What are the first steps to address this CVE?

Begin by auditing your InsightConnect environment to identify all active instances of the Sed plugin. Once located, confirm how these instances are configured and what data they process. Coordinate with your automation or platform engineering teams to prioritize these instances for updates or restricted access until a formal patch is available.

References

extensions.rapid7.com/extension/sed

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.