{"cve":"CVE-2026-84469","nvd":{"published":"2026-09-04T10:17:13.677","modified":"2026-09-15T20:06:50.543","status":"Analyzed","description":"fastify versions before 5.12.2 decide whether to compile a request schema based on JavaScript truthiness, but JSON Schema Draft 7 defines the boolean false as a valid schema that rejects every instance. When an application assigns false to a route's body, querystring, params, or headers schema to deny all input, fastify treats it as a missing schema, compiles no validator, and runs the route handler on any request. An unauthenticated remote client can therefore reach a handler that a valid deny-all schema was intended to make unreachable, a complete validation bypass that can lead to unauthorized state changes or execution of disabled operations. Users should upgrade to fastify 5.12.2 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:N/I:H/A:N","score":7.5},"cwes":["CWE-20"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fastify/security/advisories/GHSA-hwr6-493r-vm6h"],"products":["fastify:fastify"],"source":"nvd","synced_at":"2026-10-19T22:52:03.409947763+00:00"},"epss":{"cve":"CVE-2026-84469","score":0.00492,"percentile":0.42298,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-hwr6-493r-vm6h","url":"https://osv.dev/vulnerability/GHSA-hwr6-493r-vm6h","summary":"fastify vulnerable to request validation bypass via skipped boolean false schemas","modified":"2026-10-01T00:00:04.687101683Z","packages":[{"ecosystem":"npm","name":"fastify","purl":"pkg:npm/fastify","ranges":["<5.12.2"],"fixed":["5.12.2"]}]}],"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."]}