{"id":"CVE-2026-6270","state":"PUBLISHED","title":"@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes","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.","publishedAt":"2026-04-16T13:44:46.322Z","updatedAt":"2026-04-16T14:24:26.764Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"openjs"},"assigner":"openjs","products":["@fastify/middie @fastify/middie"],"affected":[{"vendor":"@fastify/middie","product":"@fastify/middie","packageURL":"pkg:npm/@fastify/middie","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"9.3.2","versionType":"semver"},{"version":"9.3.2","status":"unaffected","versionType":"semver"}]}],"references":["https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c","https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w","https://cna.openjsf.org/security-advisories.html"],"weaknesses":["CWE-436"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/6xxx/CVE-2026-6270.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-6270","state":"PUBLISHED","datePublished":"2026-04-16T13:44:46.322Z","dateUpdated":"2026-04-16T14:24:26.764Z","assignerShortName":"openjs","assignerOrgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateReserved":"2026-04-14T11:08:51.828Z"},"containers":{"cna":{"title":"@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes","descriptions":[{"lang":"en","value":"@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."}],"affected":[{"vendor":"@fastify/middie","product":"@fastify/middie","packageURL":"pkg:npm/@fastify/middie","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"9.3.2","versionType":"semver"},{"version":"9.3.2","status":"unaffected","versionType":"semver"}]}],"references":[{"url":"https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"},{"url":"https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w"},{"url":"https://cna.openjsf.org/security-advisories.html"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-436","lang":"en","description":"CWE-436: Interpretation Conflict","type":"CWE"}]}],"providerMetadata":{"shortName":"openjs","orgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateUpdated":"2026-04-16T13:44:46.322Z"},"credits":[{"lang":"en","type":"reporter","value":"FredKSchott"},{"lang":"en","type":"remediation developer","value":"climba03003"},{"lang":"en","type":"remediation developer","value":"UlisesGascon"}],"x_generator":{"engine":"cve-kit 1.0.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-16T14:23:16.690976Z","id":"CVE-2026-6270","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-16T14:24:26.764Z"}}]}}}