CVE-2026-4039 Overview
A code injection vulnerability has been identified in OpenClaw version 2026.2.19-2. This vulnerability affects the applySkillConfigenvOverrides function within the Skill Env Handler component. By manipulating input to this function, an attacker can inject and execute arbitrary code. The vulnerability is exploitable remotely over the network, making it a significant concern for organizations utilizing affected versions of OpenClaw.
Critical Impact
Remote attackers can exploit this code injection vulnerability to execute arbitrary commands on systems running vulnerable OpenClaw versions, potentially leading to unauthorized access, data theft, or complete system compromise.
Affected Products
- OpenClaw version 2026.2.19-2
- OpenClaw versions prior to 2026.2.21-beta.1
Discovery Timeline
- 2026-03-12 - CVE-2026-4039 published to NVD
- 2026-03-12 - Last updated in NVD database
Technical Details for CVE-2026-4039
Vulnerability Analysis
This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as Injection. The flaw resides in the applySkillConfigenvOverrides function of the Skill Env Handler component, where user-controlled input is not properly sanitized before being processed. This allows attackers to inject malicious code that gets executed within the context of the application.
The network-accessible attack vector combined with low attack complexity makes this vulnerability particularly concerning for internet-facing OpenClaw deployments. While authentication is required to exploit the vulnerability, once authenticated, an attacker can leverage this flaw to achieve code execution with limited confidentiality, integrity, and availability impact on the system.
Root Cause
The root cause of this vulnerability lies in insufficient input validation and sanitization within the applySkillConfigenvOverrides function. The function processes environment configuration overrides without properly neutralizing special elements that could be interpreted as code. This allows specially crafted input containing injection payloads to be processed and executed rather than treated as data.
Attack Vector
The vulnerability is exploitable via a network-based attack. An authenticated attacker can send specially crafted requests targeting the Skill Env Handler component. By manipulating the input parameters processed by the applySkillConfigenvOverrides function, the attacker can inject malicious code that will be executed by the vulnerable component.
The attack requires network access to the OpenClaw instance and valid authentication credentials. Once these prerequisites are met, exploitation involves:
- Crafting a malicious payload containing injection code
- Submitting the payload through the Skill Env Handler's configuration interface
- The vulnerable function processes the input without proper sanitization
- The injected code executes within the application context
For detailed technical information about the vulnerability and the specific fix implemented, refer to the GitHub Security Advisory and the commit that addresses this issue.
Detection Methods for CVE-2026-4039
Indicators of Compromise
- Unexpected or anomalous requests to the Skill Env Handler component containing special characters or encoded payloads
- Unusual process execution or system commands spawned by the OpenClaw application
- Error logs showing injection-related failures or unexpected input processing in applySkillConfigenvOverrides
- Network traffic patterns indicating automated exploitation attempts against OpenClaw endpoints
Detection Strategies
- Implement web application firewall (WAF) rules to detect and block code injection patterns in requests to OpenClaw
- Monitor application logs for suspicious input patterns targeting the Skill Env Handler component
- Deploy network intrusion detection systems (IDS) with signatures for common code injection techniques
- Use runtime application self-protection (RASP) to detect and prevent injection attacks in real-time
Monitoring Recommendations
- Enable verbose logging for the Skill Env Handler component to capture all configuration override requests
- Set up alerts for failed authentication attempts followed by successful logins to detect credential compromise
- Monitor for unexpected network connections initiated by the OpenClaw process
- Implement file integrity monitoring on critical OpenClaw directories to detect unauthorized modifications
How to Mitigate CVE-2026-4039
Immediate Actions Required
- Upgrade OpenClaw to version 2026.2.21-beta.1 or later immediately
- Review access controls and ensure only authorized users have access to the Skill Env Handler component
- Implement network segmentation to limit exposure of OpenClaw instances
- Audit recent logs for any signs of exploitation attempts
Patch Information
The vulnerability has been addressed in OpenClaw version 2026.2.21-beta.1. The fix is implemented in commit 8c9f35cdb51692b650ddf05b259ccdd75cc9a83c. Organizations should upgrade to the patched version as soon as possible.
Patch resources:
Workarounds
- Restrict network access to OpenClaw instances using firewall rules to limit exposure to trusted networks only
- Implement additional authentication layers or VPN requirements for accessing the Skill Env Handler
- Deploy a web application firewall with strict input validation rules to filter potentially malicious requests
- Temporarily disable or restrict access to the Skill Env Handler component if not immediately needed
# Example: Restrict network access to OpenClaw using iptables
# Allow access only from trusted internal network (adjust IP range as needed)
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
