{"id":"CVE-2026-84469","title":"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","summary":"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 …","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","cwe":["CWE-20","CWE-1287"],"vendor":"fastify","product":"fastify","affected":["fastify < 5.12.2"],"patched":["fastify 5.12.2"],"published":"2026-09-04","updated":"2026-09-15","sourceUpdated":"2026-09-15T20:06:50.543","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-84469","references":[{"url":"https://cna.openjsf.org/security-advisories.html","label":"ce714d77-add3-4f53-aff5-83d477b104bb"},{"url":"https://github.com/fastify/fastify/security/advisories/GHSA-hwr6-493r-vm6h","label":"ce714d77-add3-4f53-aff5-83d477b104bb"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84469.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-84469"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2528458"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-84469"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84469"}],"tags":["nvd","csaf","vex","red-hat"],"epss":0.00283,"epssPercentile":0.21059,"ingestedAt":"2026-09-08T19:08:49.592Z","slug":"CVE-2026-84469","body":"## Overview\n\nfastify 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.\n\n## Affected\n\n- `fastify < 5.12.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `fastify 5.12.2`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Dev Spaces · no fix planned: Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Dev Spaces · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84469.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}