# CVE-2026-61714: FluidSynth heap buffer overflow in MIDI player channel indexing

Source: https://junglewise.ai/threats/cve-2026-61714-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-61714 · Severity: high · CVSS 7.8 · Published 2026-09-18

FluidSynth is a software synthesizer that processes MIDI music files using SoundFont 2 specifications. Versions 2.2.4 through 2.5.5 contain a heap buffer overflow flaw that occurs when the MIDI channel configuration exceeds the default of 16 channels, potentially allowing an attacker to read or write memory outside the intended buffer, risking data corruption, information disclosure, or application crashes.

Technologies: [FluidSynth](https://junglewise.ai/threats/technologies/fluidsynth). Vendors: [FluidSynth](https://junglewise.ai/threats/vendors/fluidsynth).

## Quick answers

**Is CVE-2026-61714 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-61714 being exploited in the wild.

**How severe is CVE-2026-61714?** High severity, with a CVSS score of 7.8, published 18 September 2026.

**Which products and versions are affected?** FluidSynth 2.2.4 to 2.5.5.

**Is there a fix for CVE-2026-61714?** A patch was published on 2026-07-04: Fixed in version 2.5.6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-61714 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-61714?** Check whether you run FluidSynth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds heap buffer access occurs in the MIDI player's channel tracking when synth.midi-channels is configured above 16, causing reads and writes to exceed the fixed-size allocation for the _fluid_player_t::channel_isplaying array. The vulnerability is triggered by configuration alone without requiring a crafted MIDI file. The issue is fixed in FluidSynth 2.5.6 through bounds-checking on channel indexing.

## Affected products

- FluidSynth FluidSynth 2.2.4 to 2.5.5

## Timeline

- 2026-09-18: disclosed
- 2026-07-04: patched: Fixed in version 2.5.6

## References

- [https://github.com/FluidSynth/fluidsynth/commit/772702e00cc6acc7c607efb40283e2269211effc](https://github.com/FluidSynth/fluidsynth/commit/772702e00cc6acc7c607efb40283e2269211effc)
- [https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6](https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6)

## Related threats

- [FluidSynth DLS parser integer overflow](https://junglewise.ai/threats/cve-2026-61723-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth DLS articulation chunk integer overflow](https://junglewise.ai/threats/cve-2026-61722-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth DLS loader buffer overrun in sample loop processing](https://junglewise.ai/threats/cve-2026-61721-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth SF2 DMOD chunk integer underflow](https://junglewise.ai/threats/cve-2026-61720-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth heap buffer overflow in pitch_bend_range command](https://junglewise.ai/threats/cve-2026-58264-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)