4.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-40175

CVE-2026-40175: Axios has Unrestricted Cloud Metadata Exfiltration via Header Injection Chain

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.0 and 0.3.1, the Axios library is vulnerable to a specific "Gadget" attack chain that allows Prototype Pollution in any third-party dependency to be escalated into Remote Code Execution (RCE) or Full Cloud Compromise (via AWS IMDSv2 bypass). This vulnerability is fixed in 1.15.0 and 0.3.1.

(GitHub Advisory)

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CVE-2026-40175

CVE-2026-40175:

4.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
axios	npm	>= 1.0.0, < 1.15.0	1.15.0
axios	npm	< 0.31.0	0.31.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability, CVE-2026-40175, is a CRLF injection weakness in the Axios library. The root cause is improper neutralization of CRLF sequences in HTTP headers. This allows an attacker, who can pollute the Object.prototype through another vulnerability in a separate library, to inject malicious headers into requests made by Axios. This can lead to HTTP Request Smuggling, enabling attacks like cache poisoning, session hijacking, or, in this specific case, bypassing security controls for cloud metadata services like AWS IMDSv2.

The investigation of the provided patch commit 363185461b90b1b78845dc8a99a1f103d9b122a1 reveals that the core changes were made in lib/core/AxiosHeaders.js. The AxiosHeaders.set method is the primary function responsible for setting headers. Before the patch, it lacked proper validation for CRLF characters. The fix was to introduce a new validation function, assertValidHeaderValue, and call it from within AxiosHeaders.set for every header being set. This ensures that any header value containing CRLF characters will be rejected, thus preventing the injection.

The normalizeValue function was also part of the vulnerable code path, as its logic to strip only trailing CRLF characters was insufficient. While it was modified, the main fix is the proactive validation in the set method. Therefore, any runtime profile during exploitation would involve the AxiosHeaders.set function processing a maliciously crafted header value originating from a polluted prototype.

Vulnerable functions

AxiosHeaders.set

lib/core/AxiosHeaders.js

The `set` method of the `AxiosHeaders` class is responsible for setting header values. Prior to the patch, this method did not validate header values for Carriage Return Line Feed (CRLF) characters. An attacker who could control a header value (e.g., through prototype pollution) could inject CRLF characters to perform HTTP Request Smuggling. The patch introduced the `assertValidHeaderValue` function, which is called within `set` to check for and reject any header values containing these invalid characters.

normalizeValue

lib/core/AxiosHeaders.js

The `normalizeValue` function was used to process header values before they were set. The original implementation only removed trailing CRLF characters from the header value, which was insufficient to prevent HTTP Request Smuggling as CRLF characters could still be present in the middle of the value. This function was part of the vulnerable flow that allowed malicious headers to be created.

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Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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