CVE-2026-27495

Comprehensive Technical Analysis of CVE-2026-27495

1. Vulnerability Assessment and Severity Evaluation

CVE ID: CVE-2026-27495

Description: n8n, an open-source workflow automation platform, has a vulnerability in its JavaScript Task Runner sandbox. This flaw allows an authenticated user with workflow creation or modification permissions to execute arbitrary code outside the sandbox. This can lead to a full compromise of the n8n host or impact other tasks executed on the Task Runner, depending on the runner mode.

CVSS Score: 9.9

Severity Evaluation: The CVSS score of 9.9 indicates a critical vulnerability. The high score is due to the potential for complete system compromise, the ease of exploitation by authenticated users, and the significant impact on confidentiality, integrity, and availability.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Authenticated User Exploitation: An attacker with legitimate access to create or modify workflows can inject malicious code into the JavaScript Task Runner.
• Internal Task Runner Mode: If the internal Task Runner mode is enabled (default), the attacker can execute arbitrary code on the n8n host, leading to full system compromise.
• External Task Runner Mode: If the external Task Runner mode is enabled, the attacker can still impact other tasks executed on the Task Runner, potentially leading to data breaches or service disruptions.

Exploitation Methods:

• Code Injection: The attacker can inject malicious JavaScript code into the workflow, which escapes the sandbox and executes on the host system.
• Privilege Escalation: Once arbitrary code execution is achieved, the attacker can escalate privileges to gain full control over the n8n host.

3. Affected Systems and Software Versions

Affected Versions:

• n8n versions prior to 2.10.1
• n8n versions prior to 2.9.3
• n8n versions prior to 1.123.22

Affected Systems:

• Any system running the vulnerable versions of n8n with Task Runners enabled (N8N_RUNNERS_ENABLED=true).
• Systems using internal Task Runner mode are at higher risk of full compromise.

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Upgrade: Upgrade to n8n versions 2.10.1, 2.9.3, or 1.123.22 or later to remediate the vulnerability.
• Temporary Mitigations:
  • Limit workflow creation and editing permissions to fully trusted users only.
  • Use external runner mode (N8N_RUNNERS_MODE=external) to limit the impact of potential exploits.

Long-Term Mitigation:

• Implement strict access controls and regular audits of user permissions.
• Monitor and log workflow creation and modification activities for suspicious behavior.
• Regularly update and patch all software components to the latest secure versions.

5. Impact on Cybersecurity Landscape

Immediate Impact:

• Organizations using n8n for workflow automation are at risk of full system compromise, data breaches, and service disruptions.
• The vulnerability highlights the importance of secure sandboxing and access control in automation platforms.

Long-Term Impact:

• Increased awareness of the need for robust security measures in open-source automation tools.
• Potential shift towards more secure alternatives or stricter security practices within the n8n community.

6. Technical Details for Security Professionals

Vulnerability Details:

• The vulnerability exists in the JavaScript Task Runner sandbox, which fails to properly isolate code execution.
• The flaw allows code to escape the sandbox and execute on the host system, leading to arbitrary code execution.

Detection and Response:

• Detection: Implement monitoring and alerting for unusual workflow creation or modification activities. Use intrusion detection systems (IDS) to detect suspicious code execution patterns.
• Response: In case of an incident, isolate the affected n8n instance, perform a thorough forensic analysis, and apply the necessary patches and mitigations.

References:

• n8n Task Runners Configuration
• n8n Release Notes 1.123.22
• n8n Release Notes 2.10.1
• n8n Release Notes 2.9.3
• n8n Security Advisory

By addressing this vulnerability promptly and implementing robust security measures, organizations can mitigate the risk of exploitation and ensure the integrity and security of their automation workflows.