CVE-2026-9155 Overview
CVE-2026-9155 is an OS command injection vulnerability in the Rapid7 InsightConnect Sed Plugin running on Linux. Authenticated attackers can execute arbitrary operating system commands by supplying crafted input to the expression parameter. The plugin fails to validate or sanitize this user-controlled input before passing it to the underlying shell. The flaw is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command. Successful exploitation grants attackers full execution privileges in the context of the plugin process, compromising confidentiality, integrity, and availability of the host system.
Critical Impact
Authenticated attackers can execute arbitrary OS commands on the host running the Sed Plugin, leading to full system compromise within the InsightConnect workflow environment.
Affected Products
- Rapid7 InsightConnect Sed Plugin
- Linux deployments of the Sed Plugin
- InsightConnect workflows invoking the affected expression parameter
Discovery Timeline
- 2026-06-25 - CVE-2026-9155 published to NVD
- 2026-06-25 - Last updated in NVD database
Technical Details for CVE-2026-9155
Vulnerability Analysis
The Rapid7 InsightConnect Sed Plugin provides stream-editing capabilities within automated security workflows. The plugin accepts an expression parameter that is intended to carry a sed script for text transformation. Instead of restricting this parameter to valid sed syntax, the plugin passes the value directly into a shell-invoked command. An authenticated user with permission to execute the plugin can append shell metacharacters such as ;, |, $(), or backticks to inject additional commands. Those commands run with the privileges of the plugin runtime on the Linux host. Because InsightConnect plugins frequently execute with elevated service privileges and connect to integrated systems, a single injection can pivot into broader infrastructure access. The EPSS score is 0.896 percent with a percentile of 54.96 as of 2026-06-25.
Root Cause
The root cause is insufficient input validation on the expression parameter. The plugin concatenates attacker-controlled data into a shell command string without escaping, allowlisting, or invoking the underlying binary through a safe execution API that bypasses shell interpretation.
Attack Vector
Exploitation occurs over the network against an InsightConnect instance where the attacker holds valid credentials with rights to trigger the Sed Plugin. The attacker supplies a malicious expression value through a workflow execution or API call. The shell interprets the injected metacharacters and executes the embedded commands. No user interaction is required beyond the attacker's own authenticated session.
No verified proof-of-concept code is publicly available for this vulnerability. Refer to the Rapid7 Extension Overview for plugin behavior and parameter specifications.
Detection Methods for CVE-2026-9155
Indicators of Compromise
- Unexpected child processes spawned by the InsightConnect plugin runtime, such as sh, bash, curl, wget, nc, or python invocations not tied to legitimate sed operations.
- Outbound network connections from the plugin host to unfamiliar destinations following workflow executions.
- New or modified files in writable directories owned by the plugin service account.
- Audit log entries showing Sed Plugin executions containing shell metacharacters (;, |, &&, $(, backticks) in the expression field.
Detection Strategies
- Hunt for process trees where the InsightConnect plugin process is the parent of unexpected shell or interpreter binaries.
- Inspect InsightConnect job history and audit logs for expression parameter values containing command separators or substitution syntax.
- Correlate plugin execution timestamps with anomalous outbound network traffic or file system changes on the host.
Monitoring Recommendations
- Enable detailed auditing on the Linux host with auditd rules covering execve calls under the plugin service account.
- Forward plugin execution logs and host telemetry to a central SIEM for retention and correlation.
- Alert on sed plugin invocations where the expression parameter exceeds expected length or contains non-sed syntax.
How to Mitigate CVE-2026-9155
Immediate Actions Required
- Restrict execution of the Sed Plugin to trusted, least-privilege InsightConnect users until a patched version is installed.
- Review audit logs for prior Sed Plugin executions and investigate any expression values containing shell metacharacters.
- Rotate credentials and secrets accessible from the plugin host if compromise is suspected.
- Apply vendor updates to the Sed Plugin as soon as Rapid7 publishes a fixed release.
Patch Information
No patch advisory URL is included in the published NVD record at the time of writing. Monitor the Rapid7 Extension Overview page for updated plugin versions and consult Rapid7 product security communications for the corrected release.
Workarounds
- Disable the Sed Plugin in InsightConnect workflows where it is not strictly required.
- Constrain the InsightConnect role-based access control (RBAC) model so that only vetted operators can trigger Sed Plugin actions.
- Pre-validate workflow inputs upstream to reject expression values containing shell metacharacters.
- Run the plugin host with a dedicated low-privilege service account and apply Linux namespace or container isolation.
# Configuration example: auditd rule to log execve calls by the plugin service user
-a always,exit -F arch=b64 -S execve -F uid=insightconnect -k icon_sed_exec
-a always,exit -F arch=b32 -S execve -F uid=insightconnect -k icon_sed_exec
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
