CVE-2026-61714

Summary

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.2.4 until 2.5.6, configuring synth.midi-channels above 16 allows the MIDI player to index _fluid_player_t::channel_isplaying outside its fixed-size heap allocation while tracking active channels. The resulting out-of-bounds reads and writes invoke undefined behavior and may compromise confidentiality, integrity, or availability. No crafted MIDI file is required because the unsafe condition is created by the channel-count configuration itself. Keeping synth.midi-channels at its default value of 16 avoids the vulnerable path. This issue is fixed in version 2.5.6.

Affected Software

VendorProductVersion RangeStatus
FluidSynthfluidsynth>= 2.2.4, < 2.5.6affected

Weaknesses

  • CWE-122: CWE-122: Heap-based Buffer Overflow
  • CWE-125: CWE-125: Out-of-bounds Read
  • CWE-787: CWE-787: Out-of-bounds Write

References