CVE-2026-101898 in Axios
Summary
by MITRE • 09/28/2026
Axios is a promise-based HTTP client for the browser and Node.js. From 1.13.0 until 1.20.0, Axios HTTP/2 request setup does not consistently apply proxy settings and caller-supplied DNS lookup policy. An HTTPS request uses httpVersion: 2 with explicit config.proxy or environment-derived proxy settings, or relies on caller-supplied config.lookup DNS policy. The HTTP/2 path can connect without the configured proxy behavior or without applying the caller-supplied config.lookup policy before http2.connect(). Requests can bypass the intended proxy route or the caller-supplied DNS resolution policy. This issue is fixed in version 1.20.0.
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Analysis
by VulDB Data Team • 09/28/2026
The vulnerability identified within Axios versions ranging from 1.13.0 to 1.20.0 represents a critical configuration enforcement failure in the HTTP/2 request handling mechanism. Axios, widely adopted as a promise-based HTTP client for both browser environments and Node.js applications, relies on consistent application of proxy settings and DNS lookup policies to ensure secure and predictable network communication. In this specific version range, when an HTTPS request is configured with httpVersion set to 2, the library fails to consistently apply either explicit or environment-derived proxy configurations, as well as caller-supplied DNS lookup policies prior to establishing the connection via http2.connect(). This inconsistency creates a divergence between the intended security posture defined by the application developer and the actual network path taken during execution.
The technical flaw stems from an incomplete implementation of configuration propagation within the HTTP/2 transport layer. When developers specify proxy settings through explicit config.proxy parameters or rely on environment variables, these directives are designed to route traffic through a designated intermediary for inspection, logging, or security filtering. Similarly, when a custom DNS lookup policy is provided via config.lookup, it ensures that domain name resolution adheres to specific organizational constraints, such as using internal resolvers or enforcing strict validation rules. However, in the affected versions, the HTTP/2 path can initiate connections without respecting these configurations. This means that requests intended for controlled routing may instead connect directly to target hosts, bypassing security gateways and network monitoring tools entirely.
The operational impact of this vulnerability is significant, particularly in enterprise environments where proxy-based traffic inspection is a primary defense mechanism. By allowing HTTP/2 requests to circumvent configured proxies, the vulnerability enables potential data exfiltration that evades traditional perimeter defenses such as web application firewalls or secure web gateways. Furthermore, bypassing custom DNS lookup policies can lead to domain hijacking risks if the default system resolver is compromised or returns malicious IP addresses. Attackers could potentially exploit this behavior in conjunction with other vulnerabilities to redirect traffic to phishing sites or command-and-control servers without triggering alerts associated with proxy-based anomaly detection systems.
This issue aligns with CWE-20, which describes Improper Input Validation, as the library fails to properly validate and apply user-supplied configuration inputs before executing network operations. It also relates to CWE-918, where software does not enforce security-relevant settings correctly. From a tactical perspective, this behavior mirrors techniques found in MITRE ATT&CK framework under T1072, specifically Software Deployment Tools or indirect command execution via legitimate services, as it allows malicious actors to leverage trusted libraries for unauthorized network access that bypasses standard monitoring controls.
To mitigate the risks associated with this vulnerability, organizations must immediately upgrade Axios to version 1.20.0 or later, where these configuration enforcement mechanisms have been corrected. For environments unable to update immediately, implementing strict egress filtering at the network perimeter can help restrict direct HTTP/2 connections that do not pass through approved proxies. Additionally, developers should audit their codebases for any reliance on Axios HTTP/2 features and consider enforcing DNS resolution policies at a lower level in the stack if possible. Regular vulnerability scanning of dependencies is essential to ensure that such configuration bypass flaws are detected before they can be exploited in production environments.