---
id: CVE-2026-61721
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 loader assigns file-controlled
  wsmp.loop_start and wsmp.loop_length values to samples without calling
  fluid_sample_valid…
severity: high
cvss: 8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H'
cwe:
  - CWE-122
  - CWE-125
vendor: FluidSynth
product: fluidsynth
affected:
  - 'fluidsynth >= 2.5.0, < 2.5.6'
published: '2026-09-18'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T18:12:04.247'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-61721'
references:
  - url: >-
      https://github.com/FluidSynth/fluidsynth/commit/2354c2a9acdb26de7cdcd37c903ee108f46c0a7d
    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-59ph-rx8r-8p4j
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.00192
epssPercentile: 0.0785
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-18T20:21:34.730495Z'
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 loader assigns file-controlled wsmp.loop_start and wsmp.loop_length values to samples without calling fluid_sample_validate() or fluid_sample_sanitize_loop(). A crafted DLS file can place sample loop points beyond the sample buffer, causing out-of-bounds reads during audio rendering, undefined behavior, possible memory disclosure, and denial of service. Builds compiled with the CMake option enable-native-dls set to OFF do not expose the affected parser. This issue is fixed in version 2.5.6.

## Remediation

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