CVE-2026-111162 in WildMIDI
Summary
by MITRE • 10/15/2026
WildMIDI through 0.5.0 contains a heap out-of-bounds read vulnerability in the HMP parser _WM_ParseNewHmp() that allows attackers to read beyond buffers via underflowed chunk lengths. Attackers can supply a crafted .hmp file with a chunk length of 0-12 that wraps to roughly 4 GB, crashing applications or exposing heap bytes through WildMidi_GetInfo().
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in WildMIDI versions up to and including 0.5.0 represents a critical security flaw within the High Precision Music file format parser, specifically located in the _WM_ParseNewHmp() function. This component is responsible for interpreting .hmp files, which are audio formats often used in retro gaming and music synthesis applications. The core technical issue stems from an integer underflow condition during the parsing of chunk lengths. When the parser processes a crafted input file where the declared chunk length falls within the range of zero to twelve bytes, it fails to perform adequate bounds checking or unsigned arithmetic validation before proceeding with memory allocation and reading operations. This logical error allows the internal counter representing the remaining data size to wrap around due to underflow, effectively transforming a small negative value into a massive positive integer approximately equal to four gigabytes.
This heap out-of-bounds read vulnerability enables an attacker to force the application to attempt reading far beyond the allocated buffer boundaries. Because the parser believes there is significantly more data than actually exists in the file, it continues to dereference memory pointers that lie outside the legitimate allocation region of the heap. This behavior directly correlates with Common Weakness Enumeration CWE-125, which describes out-of-bounds read vulnerabilities where software reads past the end of a buffer. The exploitation of this flaw does not necessarily require code execution capabilities initially; rather, it primarily targets data confidentiality and system stability. By triggering this condition, an attacker can cause WildMIDI to expose sensitive heap contents that may contain other application variables, cryptographic keys, or internal state information through functions such as WildMidi_GetInfo().
The operational impact of this vulnerability is twofold, affecting both the availability and confidentiality aspects of security. In terms of availability, attempting to read four gigabytes of memory from a small file will inevitably lead to an access violation or segmentation fault, causing the hosting application to crash abruptly. This denial-of-service condition can disrupt services that rely on WildMIDI for real-time audio processing or background music playback in games and media players. From a confidentiality perspective, if the application does not terminate immediately upon encountering invalid memory addresses, it may leak heap data back to the attacker through error messages, log files, or network responses depending on how the calling application handles exceptions from WildMidi_GetInfo(). This information disclosure can provide attackers with valuable insights into the internal workings of the vulnerable software, potentially facilitating further exploitation attempts.
From a threat modeling perspective aligned with MITRE ATT&CK frameworks, this vulnerability falls under techniques associated with initial access and defense evasion through malformed file inputs. Attackers could distribute malicious .hmp files via email attachments, compromised websites, or game mods to trigger the flaw when users open these files in vulnerable applications. The lack of strict input validation on numeric fields like chunk lengths is a common pattern that leads to such integer overflow or underflow issues. To mitigate this risk, developers must implement rigorous input sanitization and bounds checking within the HMP parser logic. Specifically, any parsed length value should be validated against maximum allowable limits before being used for memory operations. Additionally, employing static analysis tools during development can help identify similar arithmetic vulnerabilities in other parsers. Users of WildMIDI are strongly advised to upgrade to a patched version that addresses this integer underflow issue or to restrict the use of untrusted .hmp files until an update is available.