CVE-2026-9154 Overview
CVE-2026-9154 is an arbitrary file write vulnerability in the Rapid7 InsightConnect Sed Plugin on Linux. The flaw allows authenticated attackers to write attacker-controlled content to arbitrary file paths through the expression parameter. The issue is classified as a path traversal weakness [CWE-22].
The vulnerability requires low-privilege authentication and no user interaction. Successful exploitation can compromise file integrity and disrupt availability of the underlying host. Attackers can leverage arbitrary file writes to overwrite configuration files, plant scripts, or stage follow-on code execution.
Critical Impact
Authenticated attackers can write arbitrary content to any file path accessible by the InsightConnect Sed Plugin process on Linux, enabling configuration tampering and potential privilege escalation.
Affected Products
- Rapid7 InsightConnect Sed Plugin on Linux
Discovery Timeline
- 2026-06-25 - CVE-2026-9154 published to NVD
- 2026-06-25 - Last updated in NVD database
Technical Details for CVE-2026-9154
Vulnerability Analysis
The Rapid7 InsightConnect Sed Plugin wraps the Linux sed stream editor to support automated text transformations in security orchestration workflows. The plugin accepts an expression parameter that is passed to the underlying sed process. The plugin does not adequately restrict file path references inside the supplied expression.
Attackers with valid plugin credentials can craft a sed expression containing the w command or equivalent write directive. This directive instructs sed to write processed output to an attacker-specified file path. Because the path is not validated against an allowlist or constrained to a working directory, the write operation can target any location the plugin process can reach.
The vulnerability provides high integrity impact and low availability impact according to the CVSS vector. Confidentiality is not directly affected. The flaw is exploitable over the network when the plugin endpoint is reachable through InsightConnect.
Root Cause
The root cause is improper limitation of a pathname to a restricted directory [CWE-22]. The plugin treats the expression parameter as trusted input and does not sanitize file path operators embedded within sed syntax. No canonicalization or path validation is performed before the expression reaches the sed binary.
Attack Vector
An authenticated attacker submits a malicious sed expression to the plugin through the InsightConnect workflow interface or API. The expression embeds a write directive that references a target path outside the plugin's intended scope. When the plugin executes the expression, sed writes attacker-controlled content to that path. Common targets include cron files, profile scripts, SSH authorized_keys files, or service configuration files used to chain into code execution.
No verified proof-of-concept code is publicly available. See the Rapid7 Security Extension listing for plugin details.
Detection Methods for CVE-2026-9154
Indicators of Compromise
- Unexpected modifications to system files such as /etc/cron.d/, ~/.ssh/authorized_keys, or /etc/profile.d/ originating from the InsightConnect plugin process.
- InsightConnect workflow logs containing sed expressions with the w write command targeting paths outside plugin working directories.
- New or modified files owned by the user account running the InsightConnect orchestrator.
Detection Strategies
- Audit InsightConnect workflow execution logs for expression parameter values containing file path operators or absolute paths.
- Apply Linux file integrity monitoring on sensitive directories to flag writes by the plugin service account.
- Correlate plugin invocations with subsequent file system changes outside expected output paths.
Monitoring Recommendations
- Enable verbose logging on the InsightConnect Sed Plugin and forward logs to a central analytics platform.
- Monitor process telemetry for sed invocations referencing system configuration paths.
- Alert on InsightConnect API calls submitting expressions that include w , W , or s///w patterns.
How to Mitigate CVE-2026-9154
Immediate Actions Required
- Restrict access to the InsightConnect Sed Plugin to trusted operators and rotate any shared credentials.
- Review recent plugin executions for suspicious expression parameter values and remediate any unauthorized file changes.
- Run the InsightConnect orchestrator under a least-privilege Linux account that cannot modify sensitive system files.
Patch Information
Consult the Rapid7 Security Extension listing for the current plugin version and apply the latest update from Rapid7. Verify that the deployed plugin version includes input validation for the expression parameter.
Workarounds
- Disable the Sed Plugin in InsightConnect workflows until a patched version is deployed.
- Apply Linux mandatory access controls such as AppArmor or SELinux profiles to confine the plugin process to a dedicated working directory.
- Implement an input filter in upstream workflows that rejects expression values containing write operators or absolute paths.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
