CVE-2026-103256 in n8n
Summary
by MITRE • 10/01/2026
n8n versions before 2.39.6 and 2.40.0 before 2.40.1 contain a credentials leak vulnerability in the Wekan and Baserow username-and-password credentials that sends unencrypted passwords to unvalidated hosts. Attackers with credential update permissions can modify the host field to receive account passwords at arbitrary hosts, bypassing domain validation controls.
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Analysis
by VulDB Data Team • 10/01/2026
The n8n workflow automation platform contains a critical security flaw in its handling of Wekan and Baserow credentials prior to versions 2.39.6 and 2.40.1 respectively. This vulnerability stems from an insufficient input validation mechanism within the credential management subsystem, specifically affecting how username-and-password type credentials are processed for these two integrations. The core technical flaw involves a failure to enforce strict domain or host validation when updating credential configurations. When a user with permission to update credentials modifies the configuration, the system fails to verify that the target host field corresponds to a legitimate and expected endpoint before transmitting sensitive authentication data. This oversight allows an attacker who has been granted access to modify workflow credentials to manipulate the destination address associated with these integrations.
From a technical perspective, this vulnerability represents a classic case of insecure direct object references combined with insufficient validation controls. The application trusts user-supplied input for the host field without performing adequate sanitization or verification against a whitelist of allowed domains. Consequently, when the workflow executes and attempts to authenticate using the stored credentials, it sends the unencrypted password data to an arbitrary external server controlled by the attacker rather than the intended service provider such as Wekan or Baserow. This behavior effectively bypasses any existing domain validation controls that might have been loosely configured within the application settings. The lack of encryption for passwords in transit during this specific credential update and execution flow further exacerbates the risk, although the primary issue is the misdirection of data to an untrusted host.
The operational impact of this vulnerability is severe, primarily centering on the compromise of user credentials across multiple services integrated with n8n. An attacker who gains access to a workflow editor account can exfiltrate plaintext passwords for Wekan and Baserow accounts by simply redirecting the credential transmission to their own server. This leads directly to unauthorized access to these external platforms, potentially resulting in data theft, manipulation of business-critical workflows, or further lateral movement within an organization's infrastructure if those credentials are reused elsewhere. The ability to bypass domain validation controls means that traditional perimeter defenses and internal security policies relying on trusted hostnames may fail to detect this exfiltration activity.
This vulnerability aligns with CWE-209, which describes the generation of error messages containing sensitive information, although in this case it is more accurately categorized under CWE-798: Use of Hard-coded Credentials or CWE-613: Insufficient Session Expiration if considering the broader context of credential management. More precisely, it fits CWE-942: Permissive Cross-domain Whitelist Validation and CWE-501: Trust Boundary Violation because the application fails to maintain a clear separation between trusted internal configuration data and untrusted external input regarding host destinations. In terms of the MITRE ATT&CK framework, this behavior corresponds to T1078: Valid Accounts for initial access via compromised credentials and potentially T1048: Exfiltration Over Alternative Protocol if the attacker uses non-standard channels to receive the stolen passwords. The attack vector is classified as Local with Privileges Required since it necessitates an authenticated user account with specific workflow editing permissions, making it a significant insider threat or post-exploitation risk rather than a remote unauthenticated exploit.
Mitigation strategies must focus on immediate patching and enhanced input validation practices. Organizations running affected versions of n8n should upgrade to version 2.39.6 or later for the stable branch or version 2.40.1 and above for the newer release line immediately upon availability. These updates include fixes that enforce strict host validation, ensuring that credential transmissions only occur to pre-approved and verified domains associated with Wekan and Baserow services. In addition to patching, administrators should implement rigorous access controls around workflow editing permissions, adhering to the principle of least privilege to limit who can modify credential configurations. It is also advisable to review existing workflows for any suspicious host modifications that may have occurred prior to remediation. Future development cycles should incorporate automated security testing focused on input validation and domain whitelisting to prevent similar trust boundary violations in other integrations within the platform.