CVE-2020-8251 in Node.js
Summary
by MITRE
Node.js < 14.11.0 is vulnerable to HTTP denial of service (DoS) attacks based on delayed requests submission which can make the server unable to accept new connections.
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Analysis
by VulDB Data Team • 09/19/2020
The vulnerability identified as CVE-2020-8251 affects Node.js versions prior to 14.11.0 and represents a significant denial of service weakness that specifically targets the HTTP handling mechanisms within the runtime environment. This flaw enables attackers to exploit the server's connection management system through carefully crafted delayed request submissions that consume server resources and ultimately prevent the acceptance of new incoming connections.
The technical root cause of this vulnerability lies in how Node.js handles HTTP request processing and connection lifecycle management. When an attacker submits HTTP requests with delayed data transmission, the server maintains these connections in a pending state while waiting for complete request data. This behavior creates a resource exhaustion scenario where the server's connection handling capacity becomes saturated, preventing legitimate users from establishing new connections to the service.
This vulnerability directly maps to CWE-400, which categorizes it as an Uncontrolled Resource Consumption vulnerability, specifically targeting the HTTP server's ability to manage concurrent connections effectively. The operational impact extends beyond simple service disruption, as it can lead to complete service unavailability and may be exploited as part of larger attack campaigns targeting web applications built on Node.js infrastructure. The vulnerability affects both HTTP and HTTPS servers, making it particularly dangerous in production environments where these protocols are commonly used.
The attack vector involves establishing multiple HTTP connections and then transmitting request data at a very slow rate, causing the server to maintain these connections in a waiting state indefinitely. This technique allows attackers to consume server resources such as memory and file descriptors without actually processing meaningful requests, effectively creating a resource exhaustion condition that prevents legitimate traffic from being processed.
Organizations running affected Node.js versions should immediately upgrade to version 14.11.0 or later to remediate this vulnerability. Additional mitigations include implementing connection limits, configuring appropriate timeouts for request processing, and deploying rate limiting mechanisms at the network level. From an ATT&CK framework perspective, this vulnerability aligns with the T1499.004 technique related to Network Denial of Service, and organizations should consider implementing intrusion detection systems to monitor for suspicious connection patterns that may indicate exploitation attempts.