n8n CVE-2026-103245

Exploitation requires that the target n8n instance has a workflow using the Webflow Trigger node, which exposes the unauthenticated webhook endpoint whose x-webflow-signature HMAC is not verified. No authentication, user interaction, or special attacker privileges are needed (PR:N/UI:N), and default behavior of the affected node versions is vulnerable. The key limiting factor is deployment-specific: instances without a Webflow Trigger node are not exposed at all, and the attacker must be able to reach the webhook URL (typically an internet-facing n8n). Impact is bounded to whatever downstream actions the triggered workflow performs - integrity only, no direct data read or service outage.

Moderate, integrity-focused risk. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) correctly reflects a network-reachable, low-complexity, unauthenticated flaw requiring no user interaction - the webhook endpoint is designed to receive external POSTs, so there is no authentication gate. However, impact is deliberately narrow: VC:N/VI:L/VA:N means only a low integrity impact (forged workflow triggers), with no confidentiality or availability loss, which is why the score lands at 6.9 (medium) rather than critical despite being unauthenticated and remote. My independent CVSS 3.1 assessment (~5.3, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N) agrees directionally; the gap from the 6.9 is the usual framework difference, not a dispute. No EPSS score, no CISA KEV listing, and no public exploit code are present in the data, so this is 'no public exploit identified at time of analysis' - not active exploitation. The real-world priority is tempered by the hard precondition that a Webflow Trigger node must be deployed in an active workflow; absent that node, the endpoint does not exist. This is a legitimate fix-in-maintenance-window issue, not an emergency.

An attacker who knows or discovers the n8n Webflow Trigger webhook URL (which is unauthenticated and the signature check is skipped) crafts a forged HTTP POST mimicking a Webflow event with attacker-chosen payload data. Because the x-webflow-signature HMAC is never verified, n8n accepts the forgery and executes the downstream workflow - creating bogus records, firing outbound API calls, or otherwise driving automation the attacker does not control legitimately. No exploit code is published, but the attack is trivial to script given a known endpoint.