CVE-2026-42044: Axios: Invisible JSON Response Tampering via Prototype Pollution Gadget in `parseReviver`

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-09-10
Weakness: CWE-915

Description

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.

Affected products

axios: from 1.0.0 before 1.15.1 — fixed in 1.15.1

How to fix

Upgrade to a fixed version: axios 1.15.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-42044 or the next vulnerability affects your stack