CVE-2026-25639: Axios affected by Denial of Service via __proto__ Key in mergeConfig

Axios is a promise based HTTP client for the browser and Node.js. Prior to versions 0.30.3 and 1.13.5, the mergeConfig function in axios crashes with a TypeError when processing configuration objects containing __proto__ as an own property. An attacker can trigger this by providing a malicious configuration object created via JSON.parse(), causing complete denial of service. This vulnerability is fixed in versions 0.30.3 and 1.13.5.