CVE-2021-34342 in libming
Summary
by MITRE • 03/10/2022
Ming 0.4.8 has an out-of-bounds read vulnerability in the function newVar_N() in decompile.c which causes a huge information leak.
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Analysis
by VulDB Data Team • 09/04/2025
The vulnerability identified as CVE-2021-34342 represents a critical out-of-bounds read flaw within the Ming library version 0.4.8, specifically within the decompile.c source file at the newVar_N() function. This issue arises during the decompilation process of certain binary formats, where improper bounds checking allows an attacker to access memory locations beyond the allocated buffer boundaries. The vulnerability stems from inadequate input validation and memory management practices within the decompilation engine, creating a pathway for unauthorized data exposure.
The technical implementation of this flaw demonstrates a classic buffer over-read condition that occurs when the newVar_N() function processes variable declarations during decompilation operations. When the function encounters malformed or specially crafted input data, it fails to properly validate array indices or buffer limits before accessing memory locations. This results in the function reading data from adjacent memory regions, potentially exposing sensitive information such as stack contents, heap data, or other program variables that should remain confidential. The vulnerability is particularly concerning because it operates during the decompilation phase, where the library processes potentially untrusted binary input from various sources.
The operational impact of CVE-2021-34342 extends beyond simple information disclosure, as the massive information leak could expose cryptographic keys, authentication tokens, temporary passwords, or other sensitive data elements that reside in adjacent memory locations. Attackers could exploit this vulnerability by providing malicious input to the Ming library during decompilation operations, potentially leading to complete system compromise if the leaked information includes credentials or system secrets. The vulnerability affects any application that utilizes the Ming library for binary analysis or decompilation tasks, particularly those handling untrusted input from external sources.
Security professionals should implement immediate mitigations including upgrading to a patched version of the Ming library where available, applying input validation measures to filter suspicious binary data before processing, and implementing memory protection mechanisms such as stack canaries and address space layout randomization. The vulnerability aligns with CWE-125 Out-of-Bounds Read and CWE-200 Information Disclosure, representing a significant risk to applications that process binary data. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1059 Command and Scripting Interpreter for executing malicious code and T1552 Unsecured Credentials for potential credential exposure. Organizations should conduct comprehensive security assessments of all systems utilizing the affected library version and implement monitoring for anomalous decompilation activities that might indicate exploitation attempts.