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

Synopsis

This is a header injection vulnerability in the Axios HTTP client library for Node.js and browser environments. An attacker can exploit prototype pollution in a third-party dependency to inject unsanitized values into outbound HTTP request headers, reachable over the network without any authentication. Successful exploitation gives an attacker full read access to cloud metadata endpoints (such as AWS IMDSv1), the ability to tamper with outbound requests, and can result in complete compromise of confidentiality, integrity, and availability in affected workloads. A patched-image rebuild at version 1.15.0 (or 0.31.0 for the 0.x line) is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must be able to reach the vulnerable service over the network to trigger the header injection gadget chain.

• AuthenticationNot required

  No credentials or account are needed; the exploit path requires no prior authentication to the target service.

• Victim interactionNot required

  No user action is required; the attacker can trigger the vulnerability without any involvement from a human operator or end user.

• Attack complexityDetail

  Exploitation is rated High complexity, meaning the attacker must engineer specific conditions such as a prototype pollution primitive in a co-loaded dependency before the header injection chain can fire.

Blast Radius

• Reads cloud instance metadata, including IAM role credentials from endpoints such as the AWS Instance Metadata Service, enabling credential theft and lateral movement.
• Modifies outbound HTTP request headers, allowing the attacker to forge authorization headers, override routing logic, or poison downstream services that trust those headers.
• Disrupts the affected service by injecting malformed headers that cause upstream rejections or connection termination, resulting in availability loss.
• With Scope:Changed scored, impact extends beyond the vulnerable component itself, meaning a compromised Node.js process can be used as a pivot point to reach other services within the same network trust boundary.