External risk intelligence

Rapid7 InsightConnect Sed Plugin Arbitrary File Write Vulnerability

CVE advisorySeverity: MEDIUM (CVSS 6.5)

CVE-2026-9154

The vulnerability exists in a plugin for a security orchestration tool. While it requires authentication and is not a default internet-facing gateway or public web service by design, plugins in such orchestration platforms are occasionally accessible via APIs or user interfaces that may be exposed in certain internal or edge-deployed network architectures.

Path Traversal

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 concerns an Arbitrary File Write vulnerability identified in a specific plugin used with Rapid7's InsightConnect platform on Linux systems. The issue allows authenticated users to write unintended content to various file locations on the system. The main concern is confirming relevance and exposure within our environment.

Attackers can write to any file path.
It affects authenticated users, not public access.
Confirm if this plugin is in use and exposed.

Attack Path

How an attacker could exploit the issue

An attacker with authenticated access to the Rapid7 InsightConnect Sed Plugin could exploit this vulnerability. By providing specially crafted input to the expression parameter, an attacker could write arbitrary content to any file path on the system. This could lead to unauthorized modification of system files, potentially impacting system integrity or enabling further malicious activity.

Authenticated access required.
Triggered via expression parameter input.
Risk of arbitrary file modification.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an authenticated user to write arbitrary content to any file path on the system. This occurs when the plugin is used in a context where the `expression` parameter can be controlled by an attacker.

System files could be overwritten.
Malicious content could be written to files.
Service disruption or unauthorized code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Rapid7 InsightConnect Sed Plugin vulnerability requires immediate attention from teams managing security orchestration and automation. Application owners or platform teams responsible for InsightConnect instances should initiate an inventory of all deployed plugins to identify the affected Sed Plugin. Confirming exposure and business criticality will dictate the remediation priority, involving coordination with network and security teams for access reviews and potential temporary mitigations if immediate patching is not feasible.

Own by InsightConnect platform owners.
Verify Sed Plugin usage and reachability.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the Rapid7 InsightConnect Sed Plugin?

It is a specialized extension for Rapid7 InsightConnect, a security orchestration, automation, and response (SOAR) platform. Users typically deploy this plugin on Linux-based instances to perform text-processing tasks, such as stream editing, within automated security workflows. It acts as a component that executes command-line operations to manipulate data, requiring integration into your orchestration environment to function.

What does CVE-2026-9154 mean?

This is an Arbitrary File Write vulnerability, classified as CWE-22. In plain terms, the software fails to properly sanitize input, allowing a user to write data to locations on the server they should not be able to access. Because this flaw exists within the plugin, it could allow an attacker to modify or overwrite critical system files by injecting malicious content through the software's processing functions.

How can an attacker trigger this vulnerability?

An attacker must provide specially crafted input to the 'expression' parameter within the plugin. It is important to note that this bug does not trigger through random network traffic; it requires an attacker to have authenticated access to the InsightConnect platform. If a user cannot interact with the plugin or influence this specific parameter, the vulnerability cannot be exploited.

Is my instance of InsightConnect at risk?

Halo Surface Signal indicates that while this is not a public web service, orchestration platforms often have interfaces or APIs that can be reached internally or at network edges. You should evaluate if your InsightConnect instance is accessible to users beyond the intended administrators, as any authenticated entity with control over the Sed Plugin's inputs poses a potential risk to the underlying host system.

What steps should I take if I use this plugin?

First, inventory your InsightConnect environment to confirm if the Sed Plugin is installed and active. If it is in use, identify which workflows or users have the ability to supply input to the plugin's expression parameter. Prioritize reviewing access controls for these workflows and consult with your security or platform team to determine if an update or a temporary restriction on the plugin is necessary to maintain system integrity.

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.