CVE-2021-29327 in OpenSource
Summary
by MITRE • 11/19/2021
OpenSource Moddable v10.5.0 was discovered to contain a heap buffer overflow in the fx_ArrayBuffer function at /moddable/xs/sources/xsDataView.c.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/22/2021
The heap buffer overflow vulnerability identified in OpenSource Moddable v10.5.0 represents a critical security flaw within the xsDataView.c source file, specifically affecting the fx_ArrayBuffer function. This vulnerability stems from improper memory management practices where the application fails to validate array bounds before performing memory operations, creating opportunities for attackers to manipulate heap memory structures. The flaw exists in the embedded JavaScript runtime environment that powers Moddable's development framework, making it particularly concerning for applications that rely on this technology for device-level programming and IoT implementations.
The technical implementation of this vulnerability occurs when the fx_ArrayBuffer function processes memory buffers without adequate boundary checking mechanisms. When malicious input is passed to this function, it can cause the application to write data beyond the allocated buffer space, leading to memory corruption that may result in arbitrary code execution or application crashes. This type of heap-based buffer overflow falls under the common weakness enumeration CWE-121, which specifically addresses stack-based and heap-based buffer overflow conditions. The vulnerability is particularly dangerous because it operates within the core memory management components of the runtime environment, providing attackers with potential pathways to escalate privileges or compromise the entire system.
The operational impact of this vulnerability extends beyond simple application instability, as it can enable remote code execution when exploited through crafted input data. Attackers could leverage this flaw in scenarios where Moddable applications process untrusted data from network sources, file uploads, or user input, potentially leading to complete system compromise. The vulnerability affects the embedded nature of Moddable applications, making it particularly relevant for IoT devices, smart home systems, and other embedded platforms that utilize this runtime environment. This aligns with ATT&CK technique T1059.007 for JavaScript and with T1203 for Exploitation for Client Execution, as the vulnerability enables attackers to execute malicious code within the application context.
Mitigation strategies for this vulnerability require immediate patching of the Moddable runtime to version 10.5.1 or later, which includes proper bounds checking and memory validation mechanisms. Organizations should implement input validation controls at all application layers to prevent malformed data from reaching the vulnerable function, while also establishing memory safety monitoring for embedded systems. Security teams should conduct thorough code reviews focusing on memory management practices and consider implementing address space layout randomization and stack canaries to reduce exploitability. Additionally, network segmentation and privilege separation can limit the potential impact if exploitation occurs, while regular security assessments of embedded systems can help identify similar vulnerabilities in other runtime components. The fix addresses the root cause by implementing proper buffer size validation and memory allocation checks that prevent the heap corruption conditions leading to this vulnerability.