CVE-2026-84469

The record

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.

Affected packages

Related vulnerabilities

• CVE-2026-113786 pypdf is a free and open-source pure-python PDF library. CWE-20
• CVE-2026-112081 A vulnerability was determined in hankcs HanLP up to 2.1.0-beta.64. CWE-20
• CVE-2026-111869 A vulnerability was identified in makeplane plane up to 1.4.2. CWE-20
• CVE-2026-100347 kin-openapi is a Go project for handling OpenAPI files. CWE-20
• CVE-2026-99999 In the Linux kernel, the following vulnerability has been resolved: ipv4: validate… CWE-20
• CVE-2026-107726 Hazelcast is a unified real-time data platform combining stream processing with a fast… CWE-20
• CVE-2026-105757 vLLM is an inference and serving engine for large language models. CWE-20
• CVE-2026-105756 vLLM is an inference and serving engine for large language models. CWE-20