CVE-2026-42041: Axios: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Strategy

Vulnerability summary

CVE-2026-42041 is a medium (CVSS 6.5) Improper Authentication vulnerability in axios. EPSS estimates a 0.66% chance of exploitation in the next 30 days, higher than 51.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 24-04-2026
   PublishedVulnerability first disclosed.
2. 10-09-2026
   Last modifiedVulnerability information updated.

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 is vulnerable to a Prototype Pollution "Gadget" attack that allows any Object.prototype pollution to silently suppress all HTTP error responses (401, 403, 500, etc.), causing them to be treated as successful responses. This completely bypasses application-level authentication and error handling. The root cause is that validateStatus is the only config property using the mergeDirectKeys merge strategy, which uses JavaScript's in operator — an operator that inherently traverses the prototype chain. When Object.prototype.validateStatus is polluted with () => true, all HTTP status codes are accepted as success. This vulnerability is fixed in 1.15.1 and 0.31.1.

• CWE-287Improper AuthenticationWhen an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
• CWE-1321Improperly Controlled Modification of Object Prototype AttributesThe product 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.
• CWE-915Improperly Controlled Modification of Dynamically-Determined Object AttributesThe product 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.