{"id":"CVE-2026-56357","aliases":["GHSA-mqpr-49jj-32rc"],"url":"https://o3.security/vulnerability/CVE-2026-56357","summary":"n8n - Webhook Forgery via Missing HMAC-SHA256 Signature Verification in GitHub Webhook Trigger","details":"## Impact\nAn attacker who knows the webhook URL of a workflow using the GitHub Webhook Trigger node could send unsigned POST requests and trigger the workflow with arbitrary data. The node did not implement the HMAC-SHA256 signature verification that GitHub provides to authenticate webhook deliveries, allowing any party to spoof GitHub webhook events.\n\n## Patches\nThe issue has been fixed in n8n versions 2.5.0 and 1.123.15. 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- Limit workflow creation and editing permissions to fully trusted users only.\n- Restrict network access to the n8n webhook endpoint to known GitHub webhook IP ranges.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.","published":"2026-06-22T21:04:52.333Z","modified":"2026-08-12T03:51:36.931582350Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"n8n","fixedVersion":"1.123.15"},{"ecosystem":"npm","name":"n8n","fixedVersion":"2.5.0"}],"fix":{"url":"https://github.com/n8n-io/n8n/commit/a19347a6bc9a96d5065ac77d25a811e46178c578","label":"n8n-io/n8n@a19347a"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56357.json"},{"type":"ADVISORY","url":"https://github.com/n8n-io/n8n/security/advisories/GHSA-mqpr-49jj-32rc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56357"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/n8n-webhook-forgery-via-missing-hmac-sha256-signature-verification-in-github-webhook-trigger"},{"type":"WEB","url":"https://github.com/n8n-io/n8n/commit/a19347a6bc9a96d5065ac77d25a811e46178c578"},{"type":"WEB","url":"https://github.com/n8n-io/n8n/commit/afe322325502f448b33bff1db1575e4447c28a36"},{"type":"PACKAGE","url":"https://github.com/n8n-io/n8n"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:36.931582350Z"}}