CVE-2026-54312 Overview
CVE-2026-54312 is a prototype pollution vulnerability in n8n, an open source workflow automation platform. The flaw affects all releases prior to 2.24.0. An authenticated user with permission to create or modify workflows can pollute Object.prototype process-wide by supplying a crafted value as the table parameter to the Microsoft SQL node. The pollution persists for the lifetime of the n8n server process and triggers application-wide validation failures. The instance becomes non-functional until the process is restarted. The vulnerability is tracked under [CWE-1321] and fixed in version 2.24.0.
Critical Impact
An authenticated workflow editor can render an entire n8n instance unusable through a single crafted Microsoft SQL node parameter, requiring a server restart to recover.
Affected Products
- n8n versions prior to 2.24.0
- n8n Microsoft SQL node component
- Self-hosted and cloud n8n deployments running vulnerable versions
Discovery Timeline
- 2026-06-23 - CVE-2026-54312 published to NVD
- 2026-06-23 - Last updated in NVD database
Technical Details for CVE-2026-54312
Vulnerability Analysis
The vulnerability resides in the Microsoft SQL node within n8n. The node accepts a table parameter that is processed without adequate property key sanitization. An attacker who can author or modify a workflow supplies a crafted value that traverses into special object keys such as __proto__ or constructor.prototype. The handler then writes attacker-controlled data onto Object.prototype, contaminating every object instantiated within the Node.js process.
Because n8n relies on object property checks throughout its validation pipeline, the polluted prototype causes downstream schema validators to reject legitimate input. Workflows, credentials, and API operations fail across the platform. The condition is not transient — the polluted prototype lives for the lifetime of the n8n process. Recovery requires a full restart of the n8n server.
Root Cause
The root cause is unsafe assignment using user-controlled property names inside the Microsoft SQL node's table parameter handling. The code path does not reject reserved keys (__proto__, constructor, prototype) before performing recursive merge or property assignment operations. This matches the pattern described by [CWE-1321], improperly controlled modification of object prototype attributes.
Attack Vector
The attack is network-reachable but requires authenticated access with workflow editing privileges. An attacker creates or edits a workflow that includes the Microsoft SQL node and submits a malicious table parameter. Upon node execution, the prototype is polluted globally. No further interaction is required to trigger the denial of service across the platform. See the GitHub Security Advisory GHSA-x6p3-m6h9-fx7r for vendor analysis.
No verified public exploit code is available. The vulnerability is described in prose because no sanitized proof-of-concept has been released by the vendor.
Detection Methods for CVE-2026-54312
Indicators of Compromise
- Sudden, platform-wide workflow validation failures occurring after a Microsoft SQL node execution
- n8n logs containing references to __proto__, constructor, or prototype within table parameter values
- Authenticated user activity creating or modifying workflows that include the Microsoft SQL node immediately before instance-wide failures
- Recovery of full functionality only after restarting the n8n server process
Detection Strategies
- Inspect workflow definitions stored in the n8n database for Microsoft SQL node configurations containing prototype-related keys in the table parameter
- Enable verbose audit logging on workflow create and update operations and alert on payloads containing __proto__ or constructor.prototype substrings
- Monitor n8n process error rates and correlate spikes with recent workflow modifications by authenticated editors
Monitoring Recommendations
- Track n8n version inventory and flag any instance below 2.24.0
- Forward n8n application logs to a centralized logging or SIEM platform for retention and correlation
- Alert on repeated validation failures across unrelated workflows, which indicates a polluted runtime
How to Mitigate CVE-2026-54312
Immediate Actions Required
- Upgrade n8n to version 2.24.0 or later on all self-hosted instances
- Audit existing workflows for Microsoft SQL nodes containing suspicious table parameter values and remove them
- Restart any n8n process suspected of running with a polluted prototype to restore functionality
- Review the permission model and restrict workflow create and modify privileges to trusted users only
Patch Information
The vendor fixed the issue in n8n 2.24.0. The patched release adds property key validation to reject prototype-related keys in the Microsoft SQL node table parameter. Refer to the GitHub Security Advisory GHSA-x6p3-m6h9-fx7r for the official remediation guidance.
Workarounds
- Revoke workflow create and modify permissions from non-administrative users until the upgrade is applied
- Disable or remove the Microsoft SQL node from environments where it is not required
- Place n8n behind a reverse proxy that inspects and blocks request bodies containing __proto__ or constructor.prototype patterns
# Upgrade n8n via npm
npm install -g n8n@2.24.0
# Or upgrade the official Docker image
docker pull n8nio/n8n:2.24.0
docker stop n8n && docker rm n8n
docker run -d --name n8n -p 5678:5678 n8nio/n8n:2.24.0
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
