{"cve":"CVE-2026-33807","nvd":{"published":"2026-04-15T10:16:48.310","modified":"2026-10-26T21:10:00.170","status":"Analyzed","description":"@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.\n\nUpgrade to @fastify/express v4.0.5 or later.","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/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"],"products":["fastify:fastify\\/express"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-33807","score":0.0043,"percentile":0.37012,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-hrwm-hgmj-7p9c","url":"https://osv.dev/vulnerability/GHSA-hrwm-hgmj-7p9c","summary":"@fastify/express's middleware path doubling causes authentication bypass in child plugin scopes","modified":"2026-07-08T08:14:43.215388971Z","packages":[{"ecosystem":"npm","name":"@fastify/express","purl":"pkg:npm/%40fastify/express","ranges":["<4.0.5"],"fixed":["4.0.5"]}]}],"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."]}