3.7

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-44489

CVE-2026-44489: Axios: Proxy-Authorization Header Injection via Prototype Pollution — Incomplete Null-Prototype Fix

Axios is a promise based HTTP client for the browser and Node.js. From 1.15.2 to before 1.16.0, nested objects created by utils.merge() (e.g., config.proxy) are still constructed as plain {} with Object.prototype in their chain. The setProxy() function at lib/adapters/http.js:209-223 reads proxy.username, proxy.password, and proxy.auth without hasOwnProperty checks. When Object.prototype.username is polluted, setProxy() constructs a Proxy-Authorization header with attacker-controlled credentials and injects it into every proxied HTTP request. This vulnerability is fixed in 1.16.0.

(GitHub Advisory)

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CVE-2026-44489

CVE-2026-44489:

3.7

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

SSVC / BOD 26-04 ↗

Exploitation pocAutomatable NoTech Impact Partial

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Package Name	Ecosystem	Vulnerable Versions	First Patched Version
axios	npm	= 1.15.2	1.16.0

Technical Details

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Root Cause Analysis

The vulnerability is a bypass of a previous prototype pollution fix (GHSA-q8qp-cvcw-x6jj) in Axios. The original fix protected the top-level configuration object by creating it with Object.create(null). However, this protection did not extend to nested objects, such as the proxy configuration object.

The root cause lies in two functions. First, lib/utils.js#merge is used to combine configuration objects. When a user provides a proxy object in their configuration, merge creates a new, nested object for the proxy settings as a plain {}. This new object inherits from Object.prototype, making it susceptible to prototype pollution.

Second, the lib/adapters/http.js#setProxy function reads properties like username, password, and auth from this merged proxy object without using hasOwnProperty checks. If an attacker has previously polluted Object.prototype with these properties, setProxy will incorrectly read the attacker-controlled values from the prototype chain. It then uses these values to construct a Proxy-Authorization header, which is injected into all subsequent proxied requests.

The patch addresses this by introducing strict hasOwnProperty checks in both merge and setProxy. In setProxy, a new readProxyField helper is added to ensure that only own properties of the proxy object are accessed. In merge, property reads are now guarded by hasOwnProperty to prevent polluted prototype values from being copied into the final merged configuration. This combination of fixes ensures that nested configuration objects are no longer vulnerable to prototype pollution.

Vulnerable functions

setProxy

lib/adapters/http.js

The `setProxy` function is vulnerable because it reads `proxy.username`, `proxy.password`, and `proxy.auth` properties from the configuration object without verifying if these are own properties. An attacker can pollute `Object.prototype` with malicious `username` and `password` values. When an application uses a proxy configuration, this function will read the polluted properties from the prototype chain and use them to construct and inject a `Proxy-Authorization` header into every proxied request, leading to credential injection and potential proxy access policy bypasses.

merge

lib/utils.js

The `merge` function, used for combining configuration objects, contributes to the vulnerability. It creates new nested objects as plain `{}` which inherit from `Object.prototype`. During the merge process, it reads properties from the target object (`result[targetKey]`) without an own-property check. This allows properties from a polluted `Object.prototype` to be treated as if they were part of the legitimate configuration, creating a polluted `config.proxy` object that is then passed to the `setProxy` function.

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WAF Rule

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Reasoning

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