CVE-2026-18504— fastify vulnerable to schema validation bypass via root primitive coercion mismatch

fastify vulnerable to schema validation bypass via root primitive coercion mismatch

fastify is a fast and low overhead web framework for Node.js. Versions of fastify before 5.12.1 are affected by a schema validation bypass when a request body schema targets a root primitive value. When the schema validates a top-level primitive such as an integer, Ajv can coerce a JSON string into the expected type during validation, but Fastify does not replace the root request body with the coerced value, so the route handler receives the original unvalidated string. As a result, a request that should have failed validation can reach application logic with a value that does not satisfy the schema, which can undermine integrity and access-control checks that rely on the validated type. Users should upgrade to fastify 5.12.1, which fixes the mismatch. No known workarounds are available.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

输入验证不恰当

Fastify 输入验证错误漏洞

Fastify是Fastify团队开源的一个高性能的Node.js Web框架。 Fastify 5.12.1之前版本存在输入验证错误漏洞，该漏洞源于模式验证绕过，可能导致请求体中的值未经验证而到达应用逻辑，破坏依赖验证类型的完整性和访问控制检查。

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