CVE-2020-7693 in SockJS
Summary
by MITRE
Incorrect handling of Upgrade header with the value websocket leads in crashing of containers hosting sockjs apps. This affects the package sockjs before 0.3.20.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/29/2020
The vulnerability identified as CVE-2020-7693 represents a critical security flaw in the sockjs library that impacts containerized applications hosting websocket services. This issue specifically manifests when the Upgrade header contains the value websocket, causing container crashes and service disruptions. The vulnerability affects all versions of the sockjs package prior to 0.3.20, making it a widespread concern for organizations utilizing this library in their websocket implementations. The flaw demonstrates a fundamental failure in header validation and processing logic within the library's websocket handling mechanism.
The technical root cause of this vulnerability stems from improper handling of HTTP Upgrade headers during the websocket handshake process. When a client sends an Upgrade header with the value websocket, the sockjs library fails to properly validate or process this header, leading to a crash condition that propagates to the hosting container. This behavior violates standard websocket protocol implementation practices and demonstrates a lack of proper error handling in the library's connection establishment routines. The vulnerability operates at the application layer and can be exploited through crafted HTTP requests that manipulate the Upgrade header value, making it particularly dangerous in containerized environments where service availability is paramount.
The operational impact of CVE-2020-7693 extends beyond simple service disruption to encompass potential denial of service conditions that can affect entire containerized applications. When containers hosting sockjs applications crash due to this vulnerability, it can lead to cascading failures in microservices architectures where multiple dependent services rely on websocket communication. This vulnerability directly impacts the availability and reliability of websocket-based applications, particularly in cloud-native environments where containers are frequently deployed and scaled. Organizations running sockjs applications in Kubernetes clusters, Docker containers, or other containerized platforms face significant risk of service interruptions and potential data loss during crash events.
This vulnerability aligns with CWE-20, which addresses improper input validation, and specifically relates to CWE-400, concerning unspecified resource exhaustion. The flaw also maps to ATT&CK technique T1499.004, which covers network disruption through resource exhaustion or service interruption. Organizations should prioritize immediate patching of all affected sockjs installations to version 0.3.20 or later, as this represents the first fixed release addressing the header processing flaw. Additional mitigations include implementing proper input validation at the network level, deploying intrusion detection systems to monitor for malicious Upgrade header values, and establishing container health checks that can automatically restart crashed instances. The vulnerability underscores the importance of robust header validation in websocket implementations and serves as a reminder of the critical security considerations in containerized application deployments where single points of failure can impact entire service ecosystems.