{"id":"CVE-2026-112712","summary":"@fastify/middie vulnerable to path-scoped middleware bypass via scope prefix mismatch","details":"@fastify/middie is the Express-style middleware engine for Fastify. In versions from 9.0.0 through 9.3.5, the use() function joined a path-scoped middleware's mount path to the plugin scope prefix in a way that could diverge from the path Fastify's router serves, most often when the scope prefix ended in a slash, and also for array mount paths and for mount paths written without a leading slash. When the two paths disagreed, the middleware was silently skipped while the route handler still ran, so path-scoped middleware such as authentication, authorization, or rate limiting could be bypassed by a single unauthenticated request. The issue is fixed in @fastify/middie 9.3.6, and users should upgrade to 9.3.6 or later. As a workaround, enforce authorization in a Fastify hook such as preHandler that runs after the router has resolved the request.","aliases":["GHSA-5p92-8765-9fv8"],"modified":"2026-10-21T10:45:45.566196632Z","published":"2026-10-20T20:43:48.681Z","database_specific":{"cna_assigner":"openjs","cwe_ids":["CWE-436"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/112xxx/CVE-2026-112712.json"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/112xxx/CVE-2026-112712.json"},{"type":"ADVISORY","url":"https://github.com/fastify/middie/security/advisories/GHSA-5p92-8765-9fv8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-112712"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/fastify/middie","events":[{"introduced":"d733838f145ebd88f5512aeab90784b957d8820a"},{"fixed":"a12f533be70adc06a6eed3566023c05b029e277e"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"9.0.0"},{"fixed":"9.3.6"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"}]}}],"versions":["v9.3.5","v9.3.4","v9.3.3","v9.3.2","v9.3.1","v9.3.0","v9.2.0","v9.1.0","v9.0.3","v9.0.2","v9.0.1","v9.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-112712.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}