CVE-2026-33665: n8n: LDAP email match enables permanent account takeover

n8n is an open source workflow automation platform. Prior to versions 2.4.0 and 1.121.0, when LDAP authentication is enabled, n8n automatically linked an LDAP identity to an existing local account if the LDAP email attribute matched the local account's email. An authenticated LDAP user who could control their own LDAP email attribute could set it to match another user's email — including an administrator's — and upon login gain full access to that account. The account linkage persisted even if the LDAP email was later reverted, resulting in a permanent account takeover. LDAP authentication must be configured and active (non-default). The issue has been fixed in n8n versions 2.4.0 and 1.121.0. Users should upgrade to one of these versions or later to remediate the vulnerability. If upgrading is not immediately possible, administrators should consider the following temporary mitigations: Disable LDAP authentication until the instance can be upgraded, restrict LDAP directory permissions so that users cannot modify their own email attributes, and/or audit existing LDAP-linked accounts for unexpected account associations. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

An adversary gains or already holds a low-privilege LDAP account (via phishing, credential stuffing, or insider threat). They identify the email address of an n8n administrator — often findable via LinkedIn, company directory, or OSINT. They modify their own LDAP email attribute (e.g., using self-service LDAP tools or compromised LDAP write access) to match the admin's email. On next login to n8n, the platform automatically links their LDAP identity to the admin's local account. The attacker now has full admin access, can read all stored workflow credentials (LLM API keys, database passwords, SaaS OAuth tokens), modify AI agent workflows to exfiltrate data or pivot laterally, and maintain persistent access even after reverting their LDAP email. In an AI agent context, they could silently add a webhook exfiltration step to every pipeline that processes sensitive data.