CVE-2020-37085 in VirtualTablet Server
Summary
by MITRE • 02/04/2026
VirtualTablet Server 3.0.2 contains a denial of service vulnerability that allows attackers to crash the service by sending oversized string payloads through the Thrift protocol. Attackers can exploit the vulnerability by sending a long string to the send_say() method, causing the server to become unresponsive.
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Analysis
by VulDB Data Team • 02/05/2026
The vulnerability identified as CVE-2020-37085 affects VirtualTablet Server version 3.0.2, representing a critical denial of service condition that undermines system availability and operational continuity. This flaw manifests through the Thrift protocol implementation within the server software, creating an exploitable entry point for malicious actors seeking to disrupt service operations. The vulnerability specifically targets the send_say() method, which serves as a communication endpoint for handling string data inputs from external clients. The attack vector exploits the server's inadequate input validation mechanisms, allowing adversaries to craft oversized string payloads that exceed the system's processing capabilities and trigger service instability.
The technical implementation of this vulnerability stems from insufficient bounds checking and input sanitization within the server's Thrift RPC framework. When the send_say() method receives a string payload exceeding predetermined memory allocation limits, the server process encounters a buffer overflow condition or memory exhaustion scenario. This occurs because the application fails to validate string length parameters before processing, allowing malicious inputs to consume excessive system resources or trigger memory corruption. The flaw aligns with CWE-129, which addresses improper validation of length parameters, and CWE-770, concerning allocation of resources without limits or proper checks. The vulnerability demonstrates a classic example of unchecked input handling that can lead to resource exhaustion and system instability.
Operationally, this denial of service vulnerability poses significant risks to organizations relying on VirtualTablet Server for critical tablet-based applications and services. Attackers can exploit this weakness to render the server completely unresponsive, effectively disabling all tablet communication services and potentially disrupting business operations. The impact extends beyond simple service interruption, as the vulnerability may require system restarts or manual intervention to restore normal operations, leading to extended downtime and potential revenue loss. The ease of exploitation makes this vulnerability particularly dangerous since attackers need only send a single oversized string payload to achieve their objective, requiring minimal technical expertise or resources to execute the attack successfully.
Security professionals should implement immediate mitigations including input length validation, rate limiting mechanisms, and network segmentation to isolate vulnerable services. The recommended approach involves configuring the server to reject string inputs exceeding predetermined safe limits, implementing proper error handling for malformed inputs, and establishing monitoring systems to detect unusual traffic patterns. Organizations should also consider deploying intrusion detection systems that can identify and block suspicious Thrift protocol traffic. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1595.001, involving reconnaissance for vulnerabilities. Regular security updates and patch management procedures should be enforced to prevent exploitation of known vulnerabilities, while application-level firewalls and protocol filtering can provide additional layers of protection against such attacks.