The vulnerability is a prototype pollution flaw that allows an attacker to inject malicious fields into workflow data when a public webhook is used. These injected fields are then passed to downstream built‑in nodes, causing the workflow to perform operations as if they were legitimate inputs. If the workflow contains action nodes that act on data derived from the webhook, an attacker could drive the workflow to target unintended records or send unauthorized requests using the workflow owner's credentials, effectively hijacking the workflow as a confused deputy.

This issue affects n8n‑io’s n8n platform in all releases prior to 2.25.7 and 2.26.2. Users running any earlier version that exposes public webhooks should consider this vulnerability present.

The CVSS score of 6.3 reflects the medium severity of this prototype‑pollution‑based confused‑deputy flaw. No EPSS score is available, indicating that specific exploit popularity data is not published, and the vulnerability is not listed in the CISA KEV catalog. Because the malicious payload is transmitted through a public webhook HTTP endpoint, the likely attack vector is external over the network, allowing an attacker to send a crafted request and inject arbitrary properties that are then executed by downstream nodes.