{"cve":"CVE-2026-6270","nvd":{"published":"2026-04-16T14:16:19.433","modified":"2026-06-17T11:00:34.460","status":"Analyzed","description":"@fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1},"cwes":["CWE-436"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c","https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w"],"products":["fastify:fastify\\/middie"],"source":"nvd","synced_at":"2026-10-19T22:30:49.762551342+00:00"},"epss":{"cve":"CVE-2026-6270","score":0.00498,"percentile":0.42715,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-72c6-fx6q-fr5w","url":"https://osv.dev/vulnerability/GHSA-72c6-fx6q-fr5w","summary":"@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes","modified":"2026-07-08T08:14:41.365738249Z","packages":[{"ecosystem":"npm","name":"@fastify/middie","purl":"pkg:npm/%40fastify/middie","ranges":["<9.3.2"],"fixed":["9.3.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}