CVE-2026-48931
Summary
by MITRE • 06/22/2026
A flaw in Node.js HTTP Agent can cause a client to accept as valid a response that is send before the client has sent the request.
This vulnerability affects all supported release lines: **Node.js 22**, **Node.js 24**, and **Node.js 26**.
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Analysis
by VulDB Data Team • 06/22/2026
This vulnerability in Node.js HTTP Agent represents a critical security flaw that undermines the fundamental principles of HTTP protocol compliance and connection management. The issue manifests when a client accepts responses that are sent before the client has actually transmitted its request, creating a dangerous scenario where the application processes potentially malicious or unauthorized responses. This behavior violates the expected sequential flow of HTTP communications and creates opportunities for various attack vectors including response manipulation and potential data exposure.
The technical root cause lies within the HTTP Agent implementation's handling of connection state management and response processing. When Node.js establishes connections through its HTTP Agent, it should maintain strict protocol adherence ensuring that requests are properly sent before responses are processed. However, this flaw allows for a race condition or state management issue where the agent accepts and processes responses that arrive prematurely, effectively bypassing normal request-response sequence validation. This vulnerability affects all actively supported release lines including Node.js 22, 24, and 26, indicating it is present across multiple current versions of the runtime environment.
The operational impact of this vulnerability is significant for applications relying on Node.js HTTP clients, as it creates potential attack surfaces where adversaries could exploit the improper response handling to manipulate application behavior. Applications might inadvertently process responses that were intended for different requests or connections, potentially leading to information disclosure, request smuggling, or other protocol-level attacks. This flaw particularly affects systems that depend on strict connection state management and can be exploited in scenarios involving proxy configurations, load balancers, or any environment where multiple concurrent requests are processed through shared HTTP agents.
From a cybersecurity perspective, this vulnerability aligns with CWE-1293 which addresses improper handling of response timing in network communications, and relates to ATT&CK technique T1592 for reconnaissance through information gathering. The flaw represents a degradation of the expected security posture of Node.js applications by allowing protocol violations that could be leveraged for more sophisticated attacks. Organizations should prioritize immediate patching of affected versions, as this vulnerability directly impacts the integrity of HTTP communications and could enable attackers to bypass security controls designed around proper request-response sequencing.
Mitigation strategies should include applying the latest security patches from the Node.js project immediately, implementing additional validation layers in applications that process HTTP responses, and monitoring for anomalous response patterns that might indicate exploitation attempts. Network segmentation and firewall rules can help limit the potential impact of such vulnerabilities, while application-level logging should capture any unexpected response timing behaviors to aid in detection and forensic analysis. Security teams should also consider implementing connection pooling strategies that minimize reliance on vulnerable agent configurations and maintain regular security assessments to identify similar protocol compliance issues across their Node.js applications.