CVE-2026-42035: Axios: Header Injection via Prototype Pollution

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-06-17
Weakness: CWE-113

Description

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, a prototype pollution gadget exists in the Axios HTTP adapter (lib/adapters/http.js) that allows an attacker to inject arbitrary HTTP headers into outgoing requests. The vulnerability exploits duck-type checking of the data payload, where if Object.prototype is polluted with getHeaders, append, pipe, on, once, and Symbol.toStringTag, Axios misidentifies any plain object payload as a FormData instance and calls the attacker-controlled getHeaders() function, merging the returned headers into the outgoing request. The vulnerable code resides exclusively in lib/adapters/http.js. The prototype pollution source does not need to originate from Axios itself — any prototype pollution primitive in any dependency in the application's dependency tree is sufficient to trigger this gadget. This vulnerability is fixed in 1.15.1 and 0.31.1.

Affected products

axios: before 0.31.1; from 1.0.0 before 1.15.1 — fixed in 0.31.1, 1.15.1
Npm Axios: from 1.0.0 before 1.15.1; before 0.31.1 — fixed in 1.15.1, 0.31.1

How to fix

Upgrade to a fixed version: axios 0.31.1, 1.15.1; Npm Axios 1.15.1, 0.31.1. Check the vendor advisory for mitigations.

References

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