---
id: CVE-2026-61720
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 2.5.0 until 2.5.6, the SF2 parser computes the DMOD modulator count as
  chunk.size / SF_MOD_SIZE - 1 without rejecting chunks smaller than one record.
  A cr…
severity: medium
cvss: 6.2
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-191
vendor: FluidSynth
product: fluidsynth
affected:
  - 'fluidsynth >= 2.5.0, < 2.5.6'
published: '2026-09-18'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:25:27.050'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-61720'
references:
  - url: >-
      https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44
    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-rmc4-c8hw-455w
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.00184
epssPercentile: 0.07066
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-21T16:27:05.665077Z'
ingestedAt: '2026-09-18T20:51:25.675Z'
---

## Overview

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the SF2 parser computes the DMOD modulator count as chunk.size / SF_MOD_SIZE - 1 without rejecting chunks smaller than one record. A crafted SF2 file containing a zero-sized DMOD chunk makes the unsigned subtraction wrap to UINT_MAX, and the parser then attempts billions of SFMod allocations. This exhausts process memory and causes denial of service. No workaround is available. This issue is fixed in version 2.5.6.

## Remediation

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