CVE-2026-54309 -- CVSS 10.0 Vulnerability Briefing

CVE-2026-54309 | CVSS 10.0 (Critical) | Exploit: No known exploit

What Is It

CVE-2026-54309 is an authentication bypass vulnerability in N8N's workflow automation platform, specifically affecting the @n8n/mcp-browser component when operated in HTTP transport mode.

Technical Detail

When @n8n/mcp-browser is configured to use HTTP transport mode, the MCP (Model Context Protocol) endpoint fails to enforce authentication controls on session initialization and tool invocation requests. An unauthenticated remote attacker can interact directly with the MCP endpoint to initialize sessions and invoke tools without presenting valid credentials. Depending on the tools exposed through the MCP interface, this could result in unauthorized workflow execution, data exfiltration, or broader compromise of the automation environment. The vulnerability carries a CVSS score of 10.0, reflecting the combination of network accessibility, no required authentication, and high potential impact across confidentiality, integrity, and availability.

Exploitation Status

No known exploit code has been identified at this time, and this CVE is not currently listed in CISA's Known Exploited Vulnerabilities catalog. The exploit maturity is assessed as none, meaning no public proof-of-concept or weaponized tooling has been confirmed as of June 30, 2026. However, the trivial nature of the bypass, requiring only unauthenticated HTTP requests to a known endpoint, means the barrier to exploitation is low and functional exploits could emerge quickly.

Who Is Targeting This

No specific threat actor attribution at this time. Neither confirmed nor reported threat actor activity has been associated with this vulnerability as of the current date.

What To Do

Organizations running N8N should upgrade to version 2.25.7 or 2.26.2 immediately, as these are the confirmed patched releases. Given the critical CVSS score and the unauthenticated nature of the attack vector, patching should be treated as urgent regardless of current exploitation status. As an interim workaround, administrators should avoid exposing the MCP HTTP transport endpoint to untrusted networks and restrict access via firewall rules or network segmentation to authorized hosts only. If HTTP transport mode is not operationally required, disabling it in favor of an alternative transport configuration reduces the attack surface until patching is complete. Audit logs should be reviewed for unexpected MCP session initialization events or anomalous tool invocation activity originating from external or unexpected source addresses.