libmodplug up to 0.8.9.1 MIDI Pattern Loop src/load_pat.cpp pat_smplooped smpno out-of-bounds

Summaryinfo

A vulnerability labeled as critical has been found in libmodplug up to 0.8.9.1. The impacted element is the function pat_smplooped of the file src/load_pat.cpp of the component MIDI Pattern Loop Handler. Such manipulation of the argument smpno leads to out-of-bounds. This vulnerability is uniquely identified as CVE-2026-75904. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in libmodplug up to 0.8.9.1. Affected by this issue is the function pat_smplooped of the file src/load_pat.cpp of the component MIDI Pattern Loop Handler. The manipulation of the argument smpno with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

libmodplug through 0.8.9.1 contains an out-of-bounds read in pat_smplooped in src/load_pat.cpp. The function validates only the upper bound of its sample index against MAXSMP and then subtracts one before indexing the 191-byte static array pat_loops, so an index of zero reads pat_loops[-1], one byte before the array. The index is the smpno field of a parsed MIDI event, which is initialised to zero and only later overwritten from a program-change parameter, so an event reaching the note test before an instrument is assigned carries zero. A 32-byte MIDI file supplied to the library's public ModPlug_Load entry point drives the path through CSoundFile::Create, CSoundFile::ReadMID, and MID_ReadPatterns to the read. The byte read out of bounds determines whether a note event is treated as looping, so adjacent static storage influences playback state.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-75904 since 08/18/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/18/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• libmodplug

Version

• 0.8.9.0
• 0.8.9.1

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CPE 2.2info

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