Improper access control in n8n - CVE-2026-54309
Published: June 16, 2026
Vulnerability identifier: #VU134559
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-54309
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: n8n
Affected software:
n8n
n8n
Detailed vulnerability description
The vulnerability allows a remote attacker to access browser-control capabilities and disclose sensitive information.
The vulnerability exists due to improper access control in the MCP HTTP transport endpoint when handling session initialization and tool invocation requests. A remote attacker can send crafted requests to access browser-control capabilities and disclose sensitive information.
Only instances running @n8n/mcp-browser with the HTTP transport enabled are affected. If the n8n AI Browser Bridge extension is installed and a browser connection is active, the issue can expose navigation, JavaScript evaluation, and access to browser cookies and storage in the user's real browser profile.
How to mitigate CVE-2026-54309
Install security update from vendor's website.