Описание
Axios: unbounded recursion in toFormData causes DoS via deeply nested request data
Summary
toFormData recursively walks nested objects with no depth limit, so a deeply nested value passed as request data crashes the Node.js process with a RangeError.
Details
lib/helpers/toFormData.js:210 defines an inner build(value, path) that recurses into every object/array child (line 225: build(el, path ? path.concat(key) : [key])). The only safeguard is a stack array used to detect circular references; there is no maximum depth and no try/catch around the recursion. Because build calls itself once per nesting level, a payload nested roughly 2000+ levels deep exhausts V8's call stack.
toFormData is the serializer behind FormData request bodies and AxiosURLSearchParams (used by buildURL when params is an object with URLSearchParams unavailable, see lib/helpers/buildURL.js:53 and lib/helpers/AxiosURLSearchParams.js:36). Any server-side code that forwards a client-supplied object into axios({ data, params }) therefore reaches the recursive walker with attacker-controlled depth.
The RangeError is thrown synchronously from inside forEach, escapes toFormData, and propagates out of the axios request call. In typical Express/Fastify request handlers this terminates the running request; in synchronous startup paths or worker threads it can crash the whole process.
PoC
Server-side reachability example:
Verified on axios 1.15.0 (latest, 2026-04-10), Node.js 20, 3/3 PoC runs reproduce the RangeError at depth 2500.
Impact
A remote, unauthenticated attacker who can influence an object passed to axios as request data or params triggers an uncaught RangeError inside the synchronous recursive walker. In server-side applications that proxy or re-send client JSON through axios this crashes the request handler and, in worker/cluster setups, the process. Fix by bounding recursion depth in toFormData's build function (reject or throw on depths beyond a configurable limit, e.g. 100) or rewriting the walker iteratively.
Пакеты
axios
>= 1.0.0, < 1.15.1
1.15.1
axios
<= 0.31.0
0.31.1
Связанные уязвимости
Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, toFormData recursively walks nested objects with no depth limit, so a deeply nested value passed as request data crashes the Node.js process with a RangeError. This vulnerability is fixed in 1.15.1 and 0.31.1.
Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, toFormData recursively walks nested objects with no depth limit, so a deeply nested value passed as request data crashes the Node.js process with a RangeError. This vulnerability is fixed in 1.15.1 and 0.31.1.
Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, toFormData recursively walks nested objects with no depth limit, so a deeply nested value passed as request data crashes the Node.js process with a RangeError. This vulnerability is fixed in 1.15.1 and 0.31.1.
Axios is a promise based HTTP client for the browser and Node.js. Prio ...