---
id: CVE-2026-61714
title: FluidSynth is a software synthesizer based on the SoundFont 2 specifications
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…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-125
  - CWE-787
vendor: FluidSynth
product: fluidsynth
affected:
  - 'fluidsynth >= 2.2.4, < 2.5.6'
published: '2026-09-18'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T17:17:09.700'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-61714'
references:
  - url: >-
      https://github.com/FluidSynth/fluidsynth/commit/772702e00cc6acc7c607efb40283e2269211effc
    label: security-advisories@github.com
  - url: 'https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6'
    label: security-advisories@github.com
  - url: >-
      https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-976m-35rw-h3m6
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.00184
epssPercentile: 0.07133
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-25T16:12:58.096045Z'
ingestedAt: '2026-09-18T20:51:25.674Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.