An authenticated user with workflow edit permissions can configure a Respond to Webhook node to serve binary content while manipulating the Content-Type header. The response path bypasses the central Content‑Security‑Policy sandbox, permitting a publicly accessible webhook to execute arbitrary JavaScript in the n8n origin when visited by an authenticated user. This allows an attacker to run malicious code with the privileges of the user, potentially stealing session tokens or performing further actions within the workflow platform. The vulnerability is categorized as CWE‑79, a classic cross‑site scripting weakness.

n8n by n8n-io. Versions before 1.123.55, 2.25.7, and 2.26.2 are vulnerable. The fix is available in releases 1.123.55, 2.25.7, 2.26.2 and later.

The vulnerability carries a CVSS score of 7, indicating high severity, and is not listed in the CISA KEV catalog. The EPSS score is not available, so the current exploitation probability is unknown, though the path requires an authenticated user with workflow edit rights. An attacker who can gain or already has such permissions can trigger the vulnerable node by visiting the public webhook URL, extracting the session cookie and executing JavaScript in the victim's context. The combination of authenticated access and same‑origin execution makes the risk significant for organizations that expose public webhooks or allow broad edit rights.