CVE-2026-33751: n8n: LDAP injection enables auth bypass in workflows

n8n is an open source workflow automation platform. Prior to versions 1.123.27, 2.13.3, and 2.14.1, a flaw in the LDAP node's filter escape logic allowed LDAP metacharacters to pass through unescaped when user-controlled input was interpolated into LDAP search filters. In workflows where external user input is passed via expressions into the LDAP node's search parameters, an attacker could manipulate the constructed filter to retrieve unintended LDAP records or bypass authentication checks implemented in the workflow. Exploitation requires a specific workflow configuration. The LDAP node must be used with user-controlled input passed via expressions (e.g., from a form or webhook). The issue has been fixed in n8n versions 1.123.27, 2.13.3, and 2.14.1. 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: Limit workflow creation and editing permissions to fully trusted users only, disable the LDAP node by adding `n8n-nodes-base.ldap` to the `NODES_EXCLUDE` environment variable, and/or avoid passing unvalidated external user input into LDAP node search parameters via expressions. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

An adversary targets an organization using n8n to power an AI agent that authenticates users against Active Directory before granting access to sensitive workflows. The n8n instance exposes a webhook endpoint that accepts a username parameter, which is interpolated via an expression into an LDAP search filter: (&(objectClass=user)(sAMAccountName={{$json.username}})). The attacker submits username=*)(|(objectClass=* — injecting LDAP metacharacters that transform the filter into (&(objectClass=user)(sAMAccountName=*)(|(objectClass=*)) — effectively matching all LDAP objects and bypassing the intended user-specific lookup. Depending on workflow logic, this returns the first LDAP result (often an admin account), allowing authentication bypass. Alternatively, the attacker submits username=*)(memberOf=CN=Domain Admins,DC=corp,DC=local)(* to enumerate domain admin accounts, harvesting organizational structure without credentials.