CVE-2026-111155 in LibTiMidity
Summary
by MITRE • 10/15/2026
libTiMidity through 0.2.8 contains a heap out-of-bounds read vulnerability in the SoundFont loader in src/sndfont.c that uses unvalidated sampleId and instrument generator values as table indices. Attackers can supply a crafted .sf2 file loaded through mid_set_soundfont() to read heap memory out of bounds and crash the application.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in libTiMidity versions up to 0.2.8 represents a critical security flaw within its SoundFont loading subsystem, specifically located in the source file src/sndfont.c. This component is responsible for parsing .sf2 files, which are standard formats used to define musical instrument sounds and samples for digital audio synthesis. The core technical deficiency lies in the failure of the application to perform adequate input validation on critical data fields extracted from these files before they are utilized as array indices or memory offsets. Specifically, the sampleId field and various instrument generator values, which dictate how sound samples should be mapped and processed, are accepted directly from the external file without rigorous bounds checking against the allocated heap structures.
When an attacker supplies a maliciously crafted .sf2 file containing out-of-range integer values for these identifiers, the application proceeds to use them as indices into internal data tables stored on the heap. Because the input values exceed the valid range of the target arrays or memory regions, the resulting access operation triggers a heap-based buffer over-read condition. This type of vulnerability is formally categorized under CWE-125, which describes out-of-bounds read errors where software reads past the end of a buffer. The lack of validation allows an attacker to force the program to retrieve data from arbitrary locations in memory that lie beyond the intended boundaries of the allocated soundfont structures.
The operational impact of this vulnerability is primarily characterized by application instability and potential information disclosure. In most execution scenarios, attempting to read from invalid heap addresses results in a segmentation fault or similar access violation exception, causing the host application using libTiMidity to crash abruptly. This denial-of-service effect can disrupt services relying on real-time audio processing or MIDI playback. Furthermore, depending on the specific memory layout and operating system protections, an out-of-bounds read may allow an attacker to leak sensitive information from adjacent heap allocations. Such data leakage could potentially expose internal application states, cryptographic keys, or other private user data that resides in nearby memory blocks, thereby compromising confidentiality alongside availability.
From a threat modeling perspective, this vulnerability aligns with the ATT&CK technique of T1083, which involves file and directory discovery through system utilities or APIs, although here it is specifically leveraged for information gathering via memory reads rather than direct filesystem access. The attack vector typically requires user interaction to open the malicious .sf2 file within a compatible application that utilizes libTiMidity as its backend engine. This makes social engineering or targeted delivery of crafted audio files a plausible initial access method in environments where users are expected to load custom soundfonts for music production or playback applications.
Mitigation strategies must focus on both immediate patching and long-term defensive coding practices. The most effective remediation is to upgrade libTiMidity to version 0.2.9 or later, where the developers have presumably implemented strict validation checks for sampleId and instrument generator values before they are used as indices. For applications unable to update immediately, implementing a wrapper layer that validates all incoming .sf2 data against expected maximums prior to passing it to the library can provide temporary protection. Additionally, enabling compiler-based security features such as stack protectors or heap metadata integrity checks may help detect and abort execution upon detecting memory corruption attempts. Developers should also adopt secure coding standards like CWE-134 for unchecked input handling to prevent similar issues in future development cycles.