{"id":"CVE-2026-6270","aliases":["GHSA-72c6-fx6q-fr5w"],"url":"https://o3.security/vulnerability/CVE-2026-6270","summary":"@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes","details":"@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.","published":"2026-04-16T13:44:46.322Z","modified":"2026-07-15T01:48:49.952907106Z","cvss":{"score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@fastify/middie","fixedVersion":"9.3.2"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6270.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"},{"type":"ADVISORY","url":"https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6270"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-15T01:48:49.952907106Z"}}