Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in axios

Summary

Axios is a promise based HTTP client for the browser and Node.js. Prior to 0.32.0 and 1.0.0 prior to 1.16.0, axios exposes two read-side prototype-pollution gadgets. When "Object.prototype" is polluted by an upstream dependency in the same process (e.g. lodash _.merge / CVE-2018-16487), axios silently picks up the polluted values. (1) lib/utils.js line 406 builds merge()'s accumulator as result = {}, so result[targetKey] (line 414) walks "Object.prototype" and the polluted bucket's own keys are copied into the merged headers and ride out on the wire. (2) lib/core/mergeConfig.js line 26 builds the "hasOwnProperty" descriptor as a plain-object literal. "Object.defineProperty" reads "descriptor.get/descriptor.set" via the prototype chain, so a polluted "Object.prototype.get" or "Object.prototype.set" makes the call throw "TypeError" synchronously on every axios request. This vulnerability is fixed in 0.32.0 and 1.16.0.