CVE-2021-34339 in libming
Summary
by MITRE • 03/10/2022
Ming 0.4.8 has an out-of-bounds buffer access issue in the function getString() in decompiler.c file that causes a direct segmentation fault and leads to denial of service.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/09/2025
The vulnerability identified as CVE-2021-34339 represents a critical out-of-bounds buffer access flaw within the Ming library version 0.4.8. This issue specifically manifests in the getString() function located within the decompiler.c source file, creating a dangerous condition that can result in immediate system termination through segmentation fault errors. The Ming library serves as a multimedia framework for processing and manipulating various media formats, making this vulnerability particularly concerning for applications that rely on its decompression and parsing capabilities. The flaw occurs when the library attempts to access memory beyond the allocated buffer boundaries during string processing operations, fundamentally compromising the stability and reliability of systems that utilize this component.
From a technical perspective, the vulnerability stems from inadequate bounds checking within the getString() function implementation. When the decompiler processes certain malformed or specially crafted input data, the function fails to validate buffer limits before performing memory access operations. This deficiency allows attackers to manipulate input parameters in such a way that the getString() function attempts to read or write beyond the intended memory boundaries, resulting in immediate system crashes. The segmentation fault occurs because the operating system's memory management unit detects the unauthorized memory access and terminates the process to prevent further system corruption. This behavior aligns with CWE-129, which categorizes improper validation of array indices as a fundamental flaw in input validation mechanisms, and represents a classic example of buffer overflow conditions that have plagued software systems for decades.
The operational impact of CVE-2021-34339 extends beyond simple denial of service scenarios, as it can be exploited to cause system instability and potential information disclosure in vulnerable environments. Applications that incorporate the Ming library for media processing become susceptible to remote exploitation if they fail to properly sanitize input data before passing it to the affected getString() function. This vulnerability particularly affects systems that process untrusted media content, including web servers, media processing platforms, and content management systems that rely on the library for decompression tasks. The direct segmentation fault response means that any successful exploitation will immediately terminate the target process, potentially leading to complete service disruption and requiring system administrators to restart affected services manually. According to ATT&CK framework categorization, this vulnerability maps to T1499.004 which covers network denial of service attacks, and T1059.007 for the execution of malicious code through compromised software components.
Mitigation strategies for CVE-2021-34339 should prioritize immediate patching of the Ming library to version 0.4.9 or later, which contains the necessary bounds checking fixes for the getString() function. System administrators should implement comprehensive input validation measures at all levels of their applications to prevent malformed data from reaching the vulnerable library functions. Network segmentation and access controls can help limit the potential impact of exploitation attempts by restricting access to systems that utilize the affected library. Additionally, implementing robust monitoring and alerting systems can help detect unusual process termination patterns that may indicate exploitation attempts. Organizations should also consider implementing application whitelisting policies to prevent execution of untrusted binaries that might contain malicious payloads designed to exploit this vulnerability. The fix implemented in the patched version addresses the root cause by introducing proper buffer boundary checks and ensuring that all memory access operations within the getString() function remain within allocated memory limits, thereby preventing the out-of-bounds access conditions that lead to segmentation faults and system crashes.