Prototype Pollution in Axios 1.0-1.15.1 (default transformResponse)
CVE-2026-42044 Published on April 24, 2026
Axios: Invisible JSON Response Tampering via Prototype Pollution Gadget in `parseReviver`
Axios is a promise based HTTP client for the browser and Node.js. From 1.0.0 to before 1.15.2, he Axios library is vulnerable to a Prototype Pollution "Gadget" attack that allows any Object.prototype pollution in the application's dependency tree to be escalated into surgical, invisible modification of all JSON API responses including privilege escalation, balance manipulation, and authorization bypass. The default transformResponse function at lib/defaults/index.js:124 calls JSON.parse(data, this.parseReviver), where this is the merged config object. Because parseReviver is not present in Axios defaults, not validated by assertOptions, and not subject to any constraints, a polluted Object.prototype.parseReviver function is called for every key-value pair in every JSON response, allowing the attacker to selectively modify individual values while leaving the rest of the response intact. This vulnerability is fixed in 1.15.2.
Vulnerability Analysis
CVE-2026-42044 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-42044. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.
Weakness Types
What is a Mass Assignment Vulnerability?
The software receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified.
CVE-2026-42044 has been classified to as a Mass Assignment vulnerability or weakness.
What is a Prototype Pollution Vulnerability?
The software receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
CVE-2026-42044 has been classified to as a Prototype Pollution vulnerability or weakness.
Products Associated with CVE-2026-42044
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