Affected: npm: axios

# Vulnerability Disclosure: XSRF Token Cross-Origin Leakage via Prototype Pollution Gadget in `withXSRFToken` Boolean Coercion

## Summary

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.

**Severity:** Medium (CVSS 5.4) **Affected Versions:** All versions since `withXSRFToken` was introduced **Vulnerable Component:** `lib/helpers/resolveConfig.js:59` **Environment:** Browser-only (XSRF logic only runs when `hasStandardBrowserEnv` is true)

## CWE

- **CWE-201:** Insertion of Sensitive Information Into Sent Data - **CWE-183:** Permissive List of Allowed Inputs

## CVSS 3.1

**Score: 5.4 (Medium)**

Vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N`

| Metric | Value | Justification | |---|---|---| | Attack Vector | Network | PP triggered remotely via vulnerable dependency | | Attack Complexity | Low | Once PP exists, single property assignment. Consistent with GHSA-fvcv-3m26-pcqx | | Privileges Required | None | No authentication needed | | User Interaction | Required | Victim must use browser with axios making cross-origin requests | | Scope | Unchanged | Token leakage with…