CVE-2026-42042: Axios: XSRF Token Cross-Origin Leakage via Prototype Pollution Gadget in `withXSRFToken` Boolean Coercion

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-06-17
Weakness: CWE-183

Description

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, the Axios library's XSRF token protection logic uses JavaScript truthy/falsy semantics instead of strict boolean comparison for the withXSRFToken config property. When this property is set to any truthy non-boolean value (via prototype pollution or misconfiguration), the same-origin check (isURLSameOrigin) is short-circuited, causing XSRF tokens to be sent to all request targets including cross-origin servers controlled by an attacker. This vulnerability is fixed in 1.15.1 and 0.31.1.

Affected products

axios: before 0.31.1; from 1.0.0 before 1.15.1 — fixed in 0.31.1, 1.15.1
Npm Axios: from 1.0.0 before 1.15.1; before 0.31.1 — fixed in 1.15.1, 0.31.1

How to fix

Upgrade to a fixed version: axios 0.31.1, 1.15.1; Npm Axios 1.15.1, 0.31.1. Check the vendor advisory for mitigations.

References

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