CVE-2023-49553 in MJS
Summary
by MITRE • 01/03/2024
An issue in Cesanta mjs 2.20.0 allows a remote attacker to cause a denial of service via the mjs_destroy function in the msj.c file.
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Analysis
by VulDB Data Team • 06/03/2025
The vulnerability identified as CVE-2023-49553 affects Cesanta mjs version 2.20.0, a lightweight JavaScript engine designed for embedded systems and IoT applications. This remote denial of service flaw exists within the mjs_destroy function located in the msj.c source file, representing a critical security weakness that could be exploited by attackers to disrupt system operations without requiring authentication or privileged access. The issue stems from improper handling of memory management operations during the destruction phase of JavaScript engine instances, creating conditions where malicious input could trigger abnormal program termination or resource exhaustion.
The technical root cause of this vulnerability lies in the mjs_destroy function's inadequate validation of input parameters and memory state during cleanup operations. When the function processes certain malformed or unexpected input sequences, it fails to properly handle edge cases in its internal memory deallocation routines, leading to undefined behavior that manifests as system crashes or resource exhaustion. This flaw operates at the intersection of memory management and input validation, where insufficient bounds checking and error handling in the JavaScript engine's cleanup process creates exploitable conditions. The vulnerability demonstrates characteristics consistent with CWE-476_NULL_Pointer_Dereference and CWE-121_Stack_Buffer_Overrun, as the function may attempt to access invalid memory locations or manipulate memory in ways that exceed allocated bounds.
From an operational perspective, this denial of service vulnerability presents significant risk to embedded systems, IoT devices, and network infrastructure that rely on Cesanta mjs for JavaScript execution capabilities. Remote attackers can exploit this weakness to repeatedly crash affected systems, causing service interruptions that may have cascading effects on network reliability and availability. The impact extends beyond simple system crashes to potentially affect industrial control systems, smart grid infrastructure, and connected automotive applications where continuous operation is critical. Attackers can leverage this vulnerability through network-based interactions with applications using the affected JavaScript engine, making it particularly dangerous in environments where such systems are exposed to untrusted network traffic.
Mitigation strategies for CVE-2023-49553 should prioritize immediate patching of affected systems to the latest stable version of Cesanta mjs that addresses the memory management flaw in the mjs_destroy function. Organizations should implement network segmentation and access controls to limit exposure of affected systems to untrusted networks, while also deploying intrusion detection systems to monitor for exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004_Cloud_Compute_Disruption, as it enables attackers to disrupt services through resource exhaustion or system crashes. Additional defensive measures include implementing application-level firewalls, input validation controls, and regular security assessments of embedded systems that utilize the affected JavaScript engine. System administrators should also consider implementing automated monitoring and alerting for abnormal system behavior that may indicate exploitation attempts, while maintaining detailed logs of JavaScript engine operations for forensic analysis purposes.