CVE-2019-13147 in Audio File Library
Summary
by MITRE
In Audio File Library (aka audiofile) 0.3.6, there exists one NULL pointer dereference bug in ulaw2linear_buf in G711.cpp in libmodules.a that allows an attacker to cause a denial of service via a crafted file.
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Analysis
by VulDB Data Team • 08/13/2025
The vulnerability identified as CVE-2019-13147 resides within the Audio File Library version 0.3.6, specifically within the G711.cpp module in the libmodules.a library. This flaw manifests as a NULL pointer dereference condition that occurs during the execution of the ulaw2linear_buf function. The Audio File Library is a widely used open source library designed to handle various audio file formats including those encoded using G.711 compression standards commonly employed in telephony and VoIP applications. The vulnerability represents a classic software defect where the program fails to properly validate pointer references before attempting to access memory locations, creating a potential pathway for malicious exploitation.
The technical nature of this vulnerability places it squarely within CWE-476, which categorizes NULL pointer dereferences as a fundamental programming error that can lead to application crashes or system instability. When processing a specially crafted audio file that utilizes G.711 encoding, the ulaw2linear_buf function attempts to dereference a pointer that has not been properly initialized or validated, resulting in an immediate application crash. This behavior constitutes a denial of service condition that can be reliably triggered by an attacker who controls the input file, making it particularly concerning for applications that process untrusted audio content. The vulnerability exists because the code does not perform adequate bounds checking or null validation before attempting to access memory referenced by the pointer variable.
From an operational perspective, this vulnerability poses significant risks to systems that rely on the Audio File Library for audio processing tasks. The denial of service impact means that any application using this library could become unresponsive or crash when encountering a malformed G.711 audio file, potentially disrupting services that depend on continuous audio processing capabilities. Attackers could exploit this weakness to cause service disruption in applications such as VoIP servers, audio streaming platforms, or multimedia processing systems that utilize the affected library. The vulnerability's exploitation requires minimal skill and resources, as it only necessitates crafting a specific audio file that triggers the NULL pointer dereference condition, making it particularly dangerous in environments where untrusted audio content might be processed.
Mitigation strategies for CVE-2019-13147 should focus on immediate library updates to versions that contain the necessary patches addressing the NULL pointer dereference issue. System administrators should prioritize updating the Audio File Library to the latest stable release that resolves this vulnerability, as the fix typically involves implementing proper null pointer validation before memory access operations. Additionally, input validation mechanisms should be strengthened at the application level to perform comprehensive checks on audio file headers and format specifications before passing files to the library for processing. Organizations should also consider implementing sandboxing techniques or restricted execution environments for audio processing tasks to limit the potential impact of such vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under the T1499.004 technique for 'Endpoint Denial of Service' and T1595.001 for 'Network Denial of Service', emphasizing the need for robust input validation and proper error handling mechanisms in audio processing applications.