CVE-2020-36406 in uWebSockets
Summary
by MITRE • 07/01/2021
uWebSockets 18.11.0 and 18.12.0 has a stack-based buffer overflow in uWS::TopicTree::trimTree (called from uWS::TopicTree::unsubscribeAll).
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/04/2024
The vulnerability identified as CVE-2020-36406 represents a critical stack-based buffer overflow within the uWebSockets library version 18.11.0 and 18.12.0. This flaw exists in the uWS::TopicTree::trimTree function which is invoked during the uWS::TopicTree::unsubscribeAll operation, creating a potential attack vector that could allow remote code execution or system compromise. The issue stems from improper bounds checking during memory operations within the topic tree data structure management system.
The technical implementation of this vulnerability occurs when the trimTree function processes topic subscriptions and unsubscriptions without adequate validation of input parameters or buffer boundaries. When unsubscribeAll is called, the function attempts to manipulate memory structures containing topic information, but fails to properly validate the size of operations against allocated stack buffers. This allows an attacker to craft malicious input that exceeds the allocated buffer space, causing a stack overflow condition that can overwrite adjacent memory locations including return addresses and function parameters. The vulnerability manifests through the manipulation of topic tree structures that manage subscription relationships in real-time messaging systems.
From an operational impact perspective, this vulnerability poses significant risks to applications utilizing uWebSockets for WebSocket communication and real-time data streaming. Systems that rely on this library for handling high-volume topic-based messaging are particularly vulnerable, as attackers could exploit this flaw to execute arbitrary code on affected systems. The stack overflow could lead to denial of service conditions, data corruption, or complete system compromise depending on the execution environment and privilege levels of the affected processes. Organizations running web applications, IoT systems, or real-time communication platforms that depend on uWebSockets are at risk of unauthorized access and system takeover.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory allocations where insufficient bounds checking allows attackers to overwrite adjacent memory locations. This flaw also maps to ATT&CK technique T1059.007 Command and Scripting Interpreter: Unix Shell, as exploitation could enable attackers to execute commands on compromised systems through the overflowed execution context. The mitigation strategy requires immediate patching of affected uWebSockets versions to 18.13.0 or later where the buffer overflow has been addressed through proper bounds checking and memory management. Additionally, network segmentation, input validation, and monitoring for anomalous subscription/unsubscription patterns should be implemented as defensive measures to reduce the attack surface and detect potential exploitation attempts.
This vulnerability demonstrates the critical importance of proper memory management in high-performance networking libraries where real-time processing demands can sometimes lead to oversight in security controls. The flaw represents a classic example of how seemingly minor implementation details in memory handling can create significant security risks in widely-used open-source components. Organizations should implement comprehensive patch management processes to ensure timely updates of all networking libraries and frameworks to prevent exploitation of similar vulnerabilities in their infrastructure.