CVE-2025-31951: HCL BigFix RunBookAI RCE Vulnerability

CVE-2025-31951 Overview

CVE-2025-31951 is a command injection vulnerability affecting HCL BigFix RunBookAI. The flaw stems from unvalidated command input handling within a product component, enabling potential command smuggling. An authenticated attacker with low privileges can inject crafted input that the application interprets as operating system or application commands. Successful exploitation leads to unauthorized command execution on the affected system.

The weakness is classified under [CWE-77] Improper Neutralization of Special Elements used in a Command. The vulnerability is exploitable over the network with low attack complexity and no user interaction required.

Critical Impact

Authenticated network attackers can execute arbitrary commands through smuggled input, compromising confidentiality, integrity, and availability of the BigFix RunBookAI host.

Affected Products

• HCL BigFix RunBookAI
• Refer to the HCL Software Knowledge Base Article for affected version ranges
• Deployments exposing the RunBookAI component to authenticated users

Discovery Timeline

• 2026-05-06 - CVE-2025-31951 published to NVD
• 2026-05-06 - Last updated in NVD database

Technical Details for CVE-2025-31951

Vulnerability Analysis

HCL BigFix RunBookAI processes input that is passed to a command execution context without adequate neutralization of special elements. Attackers can append delimiters, shell metacharacters, or chained command sequences that the underlying interpreter processes as separate instructions. This pattern is consistent with classic command smuggling, where adversary-controlled data crosses a trust boundary into a command-building routine.

Because exploitation requires only low privileges over the network, any authenticated user account, including ones obtained through credential reuse or phishing, becomes a viable foothold. The resulting command execution runs in the context of the RunBookAI service. That context typically has access to automation runbooks, endpoint orchestration capabilities, and stored credentials, amplifying downstream risk across the BigFix-managed estate.

Root Cause

The root cause is improper neutralization of special elements supplied to a command-building component [CWE-77]. Input is concatenated into a command string or passed to a shell-invoking API without strict allow-listing, parameterized execution, or argument-array invocation. Any character class that the downstream interpreter treats as a separator, such as ;, |, &, backticks, or $(), can be smuggled through validation routines.

Attack Vector

An attacker authenticates to the RunBookAI interface or API and submits crafted parameters that contain command-control characters. The vulnerable component forwards the tainted input to an OS command, scripting engine, or automation handler. The interpreter executes the smuggled commands with the privileges of the service account. No additional user interaction is required, and the attack succeeds across the network.

No verified public proof-of-concept code is available for this issue. See the HCL Software Knowledge Base Article for vendor technical details.

Detection Methods for CVE-2025-31951

Indicators of Compromise

• Unexpected child processes spawned by the BigFix RunBookAI service account, especially shells (cmd.exe, powershell.exe, /bin/sh, /bin/bash).
• HTTP requests to RunBookAI endpoints containing shell metacharacters such as ;, |, &&, backticks, or $() in parameter values.
• New scheduled tasks, services, or cron entries created shortly after RunBookAI API activity.
• Outbound network connections from the RunBookAI host to unfamiliar IP addresses or domains following authenticated sessions.

Detection Strategies

• Inspect web server and application logs for parameter values containing command separators or encoded equivalents (%3B, %7C, %26).
• Correlate authentication events on RunBookAI with subsequent process creation events on the host.
• Hunt for anomalous command lines invoked by the RunBookAI parent process across endpoint telemetry.

Monitoring Recommendations

• Enable verbose audit logging on RunBookAI API endpoints and forward logs to a centralized SIEM.
• Alert on process tree deviations where the RunBookAI service spawns interpreters or network utilities such as curl, wget, or nc.
• Monitor file integrity on RunBookAI configuration directories and runbook script paths.

How to Mitigate CVE-2025-31951

Immediate Actions Required

• Apply the vendor remediation referenced in the HCL Software Knowledge Base Article as soon as possible.
• Restrict network access to the RunBookAI management interface to trusted administrative subnets.
• Rotate credentials for accounts with RunBookAI access and enforce multi-factor authentication.
• Review recent runbook executions and audit logs for signs of abuse.

Patch Information

HCL has published remediation guidance in knowledge base article KB0130444. Administrators should consult the HCL Software Knowledge Base Article to identify fixed versions and apply the corresponding update to all RunBookAI instances.

Workarounds

• Limit RunBookAI accounts to the minimum number of users required for operations.
• Place the RunBookAI host behind a reverse proxy or web application firewall configured to block requests containing shell metacharacters.
• Disable or quarantine RunBookAI functionality until the vendor patch can be applied if exposure cannot be reduced through network controls.

# Example firewall rule restricting RunBookAI access to an admin subnet
iptables -A INPUT -p tcp --dport 443 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP