CVE-2026-67319: axios before 0.33.0 Prototype Pollution via nested option objects

Severity: low (CVSS 3.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-01 · updated 2026-09-01
Weakness: CWE-1321

Description

axios before 0.33.0 (and 1.x before 1.18.0) can consume inherited properties from nested request option objects when the JavaScript process's Object.prototype has already been polluted by another component. While the top-level merged config uses a null prototype, nested plain objects such as auth and paramsSerializer are cloned into ordinary objects and read without own-property checks. When an application passes placeholder nested objects such as auth: {} or paramsSerializer: {}, inherited username/password values can cause silent injection of an Authorization: Basic header, and inherited encode/serialize values can alter query-string serialization (full serializer replacement requires a function-valued pollution primitive). This is exploitable only in the presence of pre-existing prototype pollution.

Affected products

axios: before 0.33.0; from 1.0.0 before 1.18.0 — fixed in 0.33.0, 1.18.0
Npm Axios: from 0.8.0 before 0.33.0; from 1.0.0 before 1.18.0 — fixed in 0.33.0, 1.18.0

How to fix

Upgrade to a fixed version: axios 0.33.0, 1.18.0; Npm Axios 0.33.0, 1.18.0. Check the vendor advisory for mitigations.

References

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