{"id":"GHSA-679f-58pq-4v2c","summary":"n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service","details":"## Impact\n\nThe Instance AI workflow summary built its result with get-or-create-then-nested-write idioms keyed by node names and connection keys taken from the stored workflow. Those are arbitrary strings: the restricted-name guard n8n shows in the editor is client-side and is bypassed by posting the workflow to the REST API directly. So a reserved key such as `__proto__` resolved up the prototype chain instead of creating an own key, and the write landed on `Object.prototype` in the main n8n process, affecting every later request. The patch builds the summary with null-prototype accumulators and validates the keys it accepts, so reserved names cannot reach the prototype chain.\n\n## Patches\n\nThe issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.\n\n## Workarounds\n\nIf upgrading is not immediately possible, administrators should consider the following temporary mitigations:\n- Restrict n8n instance access to fully trusted users only.\n- Remove or leave unconfigured the `N8N_INSTANCE_AI_MODEL*` environment variables to prevent the Instance AI module from reaching the vulnerable code path.\n- Restart the n8n process to clear any in-memory prototype pollution if an attack is suspected.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.","aliases":["CVE-2026-86078"],"modified":"2026-09-10T21:15:05.060140700Z","published":"2026-09-10T21:05:24Z","database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-09-10T21:05:24Z","nvd_published_at":"2026-09-08T22:19:16Z","cwe_ids":["CWE-1321"]},"references":[{"type":"WEB","url":"https://github.com/n8n-io/n8n/security/advisories/GHSA-679f-58pq-4v2c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86078"},{"type":"PACKAGE","url":"https://github.com/n8n-io/n8n"},{"type":"WEB","url":"https://github.com/n8n-io/n8n/releases/tag/n8n@2.37.7"},{"type":"WEB","url":"https://github.com/n8n-io/n8n/releases/tag/n8n@2.38.2"}],"affected":[{"package":{"name":"n8n","ecosystem":"npm","purl":"pkg:npm/n8n"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.38.0"},{"fixed":"2.38.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-679f-58pq-4v2c/GHSA-679f-58pq-4v2c.json"}},{"package":{"name":"n8n","ecosystem":"npm","purl":"pkg:npm/n8n"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.37.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-679f-58pq-4v2c/GHSA-679f-58pq-4v2c.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}