n8n: DOM-Based XSS via Unsandboxed iframe srcdoc in HTML Preview

## Impact The HTML preview renders execution output into an `iframe srcdoc` without `sandbox`, so a sanitizer bypass lets injected script run same-origin as the editor. When a victim opens the preview, it can call authenticated APIs with their session. An account with `global:member` privileges can exploit it. ## Patches The issue has been fixed in n8n versions 1.123.64, 2.29.8, and 2.30.1. Users should upgrade to one of these versions or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Restrict n8n instance access to fully trusted users only. - Set the `N8N_CONTENT_SECURITY_POLICY` environment variable to a policy that blocks inline scripts. - Avoid exposing workflows that render externally-controlled input into the HTML node or binary HTML preview to untrusted users. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

Source published

22 Jul 2026 17:57:14 UTC

Source modified

22 Jul 2026 19:03:13 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

Publisher rating · HIGH