{"id":"CVE-2026-42230","aliases":["GHSA-f6x8-65q6-j9m9"],"url":"https://o3.security/vulnerability/CVE-2026-42230","summary":"n8n: Open Redirect in MCP OAuth Consent Flow","details":"## Impact\nThe `/mcp-oauth/register` endpoint accepted OAuth client registrations without authentication, allowing arbitrary `redirect_uri` values to be registered. When a user denies the MCP OAuth consent dialog, the `handleDeny` handler redirects the user to the registered `redirect_uri` without validation, enabling an open redirect to an attacker-controlled URL. An attacker can craft a phishing link and send it to a victim; if the victim clicks \"Deny\" on the consent page, they are silently redirected to an external site.\n\n## Patches\nThe issue has been fixed in n8n versions 1.123.32, 2.17.4, and 2.18.1. Users should upgrade to one of these versions or later to remediate the vulnerability.\n\n## Workarounds\nIf upgrading is not immediately possible, administrators should consider the following temporary mitigations:\n- Restrict network access to the n8n instance to prevent untrusted users from reaching the MCP OAuth endpoints.\n- Limit access to the n8n instance to fully trusted users only.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.","published":"2026-05-04T18:28:43.069Z","modified":"2026-08-12T03:51:19.282450172Z","cvss":null,"epss":{"score":0.00181,"percentile":0.07907,"asOf":"2026-08-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"n8n","fixedVersion":"1.123.32"},{"ecosystem":"npm","name":"n8n","fixedVersion":"2.18.1"},{"ecosystem":"npm","name":"n8n","fixedVersion":"2.17.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42230.json"},{"type":"ADVISORY","url":"https://github.com/n8n-io/n8n/security/advisories/GHSA-f6x8-65q6-j9m9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42230"},{"type":"PACKAGE","url":"https://github.com/n8n-io/n8n"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.282450172Z"}}