---
id: CVE-2026-61722
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 native DLS parser validates articulation chunks
  using the unsigned expression cbsize + connblocks * 12 without first ensuring
  that …
severity: medium
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'
cwe:
  - CWE-190
vendor: FluidSynth
product: fluidsynth
affected:
  - 'fluidsynth >= 2.5.0, < 2.5.6'
published: '2026-09-18'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T18:28:25.093'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-61722'
references:
  - url: >-
      https://github.com/FluidSynth/fluidsynth/commit/4d7084fca7c876f5d738498b4917a39faf603425
    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-hp72-35pr-6h6r
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.00198
epssPercentile: 0.08424
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-22T15:43:44.365934Z'
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 native DLS parser validates articulation chunks using the unsigned expression cbsize + connblocks * 12 without first ensuring that the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large connblocks value that wraps the expression and bypasses the chunk-size check, after which the parser performs approximately one billion 12-byte iterations beyond the chunk boundary. The excessive processing and invalid reads can cause denial of service. Builds with the CMake option enable-native-dls set to OFF do not expose the parser. This issue is fixed in version 2.5.6.

## Remediation

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