# Axios uncontrolled recursion in formDataToJSON denial of service

Source: https://junglewise.ai/threats/axios-uncontrolled-recursion-in-formdatatojson-denial-of-service-99f685fa  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-01. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 6.3 · Published 2026-08-01

Axios is a widely-used HTTP client library used by Node.js applications to make requests. The library contains a flaw in how it processes form data fields with excessively nested names, allowing an attacker to crash the server process with a specially crafted request. This denial-of-service vulnerability affects any application that sends untrusted user-submitted form data through Axios, potentially disrupting service availability for all users.

Technologies: [Axios](https://junglewise.ai/threats/technologies/axios). Vendors: [Axios](https://junglewise.ai/threats/vendors/axios).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 6.3, published 1 August 2026.

**Which products and versions are affected?** Axios 0.28.0 to 0.32.x, 1.0.0 to 1.17.x.

**Is there a fix for This vulnerability?** A patch was published on 2026: Patches available in versions 0.33.0 and 1.18.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run Axios at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the buildPath() function within lib/helpers/formDataToJSON.js, which recursively processes bracket-delimited segments in FormData key names without enforcing a maximum recursion depth. The parsePropPath() function extracts segments from keys like "a[x][x][x]" by splitting on brackets; a malicious key with 15,000+ nested bracket pairs results in 15,000+ recursive calls, exceeding the V8 JavaScript engine's default call stack limit (~10,000–15,000 frames) and throwing an unrecoverable RangeError. The vulnerability is reachable via two code paths: direct calls to the public axios.formToJSON() API and internal transformation when FormData is serialized to JSON (Content-Type: application/json). The inverse function toFormData already enforces a maxDepth limit; formDataToJSON lacks this guard. Patches are available in versions 0.33.0 and 1.18.0.

## Affected products

- axios axios 0.28.0 to 0.32.x, 1.0.0 to 1.17.x

## Timeline

- 2026-07-06: disclosed: Original advisory GHSA-pmv8-rq9r-6j72 published
- 2026-08-01: advisory: Duplicate advisory GHSA-4ww2-rjh2-xpv9 published
- 2026: patched: Patches available in versions 0.33.0 and 1.18.0

## References

- [https://github.com/axios/axios/security/advisories/GHSA-pmv8-rq9r-6j72](https://github.com/axios/axios/security/advisories/GHSA-pmv8-rq9r-6j72)
- [https://www.vulncheck.com/advisories/axios-before-denial-of-service-via-formtojson](https://www.vulncheck.com/advisories/axios-before-denial-of-service-via-formtojson)

## Related threats

- [Axios NO_PROXY CIDR notation bypass in Node.js adapter](https://junglewise.ai/threats/cve-2026-101899-axios-cidr-form-no-proxy-entries-are-ignored-causing-proxy)
- [Axios prototype pollution in ToFormData](https://junglewise.ai/threats/cve-2026-101909-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios fetch adapter header injection via prototype pollution](https://junglewise.ai/threats/cve-2026-101908-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios fetch adapter maxRedirects bypass](https://junglewise.ai/threats/cve-2026-101907-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios ReDoS in shouldBypassProxy regular expression](https://junglewise.ai/threats/cve-2026-101906-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)