n8n Vulnerable to XSS via Binary Data Inline HTML Rendering
Medium8.9CVE-2026-33749 · Published Mar 26, 2026
## Impact An authenticated user with permission to create or modify workflows could craft a workflow that produces an HTML binary data object without a filename. The `/rest/binary-data` endpoint served such responses inline on the n8n origin without `Content-Disposition` or `Content-Security-Policy` headers, allowing the HTML to render in the browser with full same-origin JavaScript access. By sending the resulting URL to a higher-privileged user, an attacker could execute JavaScript in the victim's authenticated session, enabling exfiltration of workflows and credentials, modification of workflows, or privilege escalation to admin. ## Patches The issue has been fixed in n8n versions 1.123.27, 2.13.3, and 2.14.1. 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: - Limit workflow creation and editing permissions to fully trusted users only. - Restrict network access to the n8n instance to prevent untrusted users from accessing binary data URLs. These workarounds do not fully remediate the risk and should only be used as...
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| n8n npm | < 1.123.27 | 1.123.27 |
| >= 2.14.0, < 2.14.1 | 2.14.1 | |
| >= 2.0.0-rc.0, < 2.13.3 | 2.13.3 |
Details and references
## Impact An authenticated user with permission to create or modify workflows could craft a workflow that produces an HTML binary data object without a filename. The `/rest/binary-data` endpoint served such responses inline on the n8n origin without `Content-Disposition` or `Content-Security-Policy` headers, allowing the HTML to render in the browser with full same-origin JavaScript access. By sending the resulting URL to a higher-privileged user, an attacker could execute JavaScript in the victim's authenticated session, enabling exfiltration of workflows and credentials, modification of workflows, or privilege escalation to admin. ## Patches The issue has been fixed in n8n versions 1.123.27, 2.13.3, and 2.14.1. 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: - Limit workflow creation and editing permissions to fully trusted users only. - Restrict network access to the n8n instance to prevent untrusted users from accessing binary data URLs. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L
- Severity from
- GitHub (reviewed advisory)
- Weakness
- CWE-79
- Also known as
- CVE-2026-33749
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|---|---|---|---|
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| Mar 25 | n8n Has External Secrets Authorization Bypass in Credential SavingHigh6.3Mar 25 | High6.3 | 1.123.23+1 more |
| Mar 25 | n8n Has Authorization Bypass in OAuth Callback via N8N_SKIP_AUTH_ON_OAUTH_CALLBACKMedium4.7Mar 25 | Medium4.7 | 2.8.0 |