axios : Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) V - CVE-2026-101908

Axios is a promise-based HTTP client for the browser and Node.js. From 1.7.0 until 1.20.0 the fetch adapter constructs a Request with sanitized resolvedOptions but then calls fetch with the original fetchOptions. A separate same-process prototype-pollution flaw populates Object.prototype.headers so fetchOptions.headers resolves through inheritance. The inherited fetchOptions.headers value overrides the sanitized Request headers through the second argument to fetch after Request construction. At