FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS loader assigns file-controlled wsmp.loop_start and wsmp.loop_length values to samples without calling fluid_sample_validate() or fluid_sample_sanitize_loop(). A crafted DLS file can place sample loop points beyond the sample buffer, causing out-of-bounds reads during audio rendering, undefined behavior, possible memory disclosure, and denial of service. Builds compiled with the CMake option enable-native-dls set to OFF do not expose the affected parser. This issue is fixed in version 2.5.6.

Affected: openEuler:24.03-LTS-SP4: fluidsynth

FluidSynth is a free software synthesizer. Its currently based on the SoundFont 2 specifications and supports real time MIDI effect controls. It can be used as a shared library for embedding in other applications, can play MIDI files and has a command line shell. Many other applications use FluidSynth for audio synthesis. Security Fix(es):

A heap-based buffer overflow was discovered in fluidsynth's MIDI player. When the synth is configured with `synth.midi-channels > 16` an out-of-bounds memory access is performed on the array `_fluid_player_t::channel_isplaying` in heap memory invoking undefined behavior. No crafted MIDI file is required to expose this vulnerability.(CVE-2026-61714)

An unsigned integer overflow in fluidsynth's SF2 parser was discovered. The DMOD chunk handler calculates modulator count as `chunk.size / SF_MOD_SIZE - 1`. When `chunk.size = 0`, the division yields 0 and the unsigned subtraction wraps to `UINT_MAX` (4,294,967,295). The guard check passes because `0 % 10 == 0`. The loop iterates billions of times, allocating an `SFMod` struct per iteration until causing a denial of service via out-of-memory.(CVE-2026-61720)

Fluidsynth's native DLS loader sets sample loop points from file-sourced `wsmp.loop_start` and `wsmp.loop_length` values without calling `fluid_sample_validate()` or `fluid_sample_sanitize_loop()`. Crafted DLS files with loop values exceeding the sample buffer cause out-of-bounds reads during audio rendering, invoking…

Affected: Ubuntu:14.04:LTS: fluidsynth, Ubuntu:16.04:LTS: fluidsynth, Ubuntu:18.04:LTS: fluidsynth, Ubuntu:20.04:LTS: fluidsynth, Ubuntu:22.04:LTS: fluidsynth, Ubuntu:24.04:LTS: fluidsynth, Ubuntu:26.04:LTS: fluidsynth

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS loader assigns file-controlled wsmp.loop_start and wsmp.loop_length values to samples without calling fluid_sample_validate() or fluid_sample_sanitize_loop(). A crafted DLS file can place sample loop points beyond the sample buffer, causing out-of-bounds reads during audio rendering, undefined behavior, possible memory disclosure, and denial of service. Builds compiled with the CMake option enable-native-dls set to OFF do not expose the affected parser. This issue is fixed in version 2.5.6.