---
id: CVE-2026-58264
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 1.1.2 until 2.5.6, the FluidSynth command handler accepts a
  pitch_bend_range command whose channel argument is not bounds checked before
  the supplied valu…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
vendor: FluidSynth
product: fluidsynth
affected:
  - 'fluidsynth >= 1.1.2, < 2.5.6'
published: '2026-09-18'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T20:17:18.107'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58264'
references:
  - url: >-
      https://github.com/FluidSynth/fluidsynth/commit/762a3bd39a431cd45abf3bbcce7286c87909d087
    label: security-advisories@github.com
  - url: 'https://github.com/FluidSynth/fluidsynth/pull/1796'
    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-mqmq-w63q-cj94
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-18T20:51:25.674Z'
epss: 0.00586
epssPercentile: 0.4643
---

## Overview

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 1.1.2 until 2.5.6, the FluidSynth command handler accepts a pitch_bend_range command whose channel argument is not bounds checked before the supplied value is written through the selected synth channel. An out-of-range channel can therefore cause an out-of-bounds heap write, leading to denial of service or possible code execution. The issue is remotely reachable when the TCP server is enabled through new_fluid_server() or fluidsynth -s, and it is locally reachable through malicious commands delivered to the FluidSynth shell on standard input. Applications that do not use the shell, command handler, or TCP server are not affected. This issue is fixed in version 2.5.6.

## Remediation

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