# CVE-2026-61723: FluidSynth DLS parser integer overflow

Source: https://junglewise.ai/threats/cve-2026-61723-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-61723 · Severity: medium · CVSS 6.8 · Published 2026-09-18

FluidSynth is a software synthesizer that reads and plays sound files in DLS format. A flaw in the DLS parser allows an attacker to create a malicious sound file that causes the application to allocate massive amounts of memory and read far beyond file boundaries when the file is opened or parsed, leading to denial of service or application crash.

Technologies: [FluidSynth](https://junglewise.ai/threats/technologies/fluidsynth). Vendors: [FluidSynth](https://junglewise.ai/threats/vendors/fluidsynth).

## Quick answers

**Is CVE-2026-61723 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-61723 being exploited in the wild.

**How severe is CVE-2026-61723?** Medium severity, with a CVSS score of 6.8, published 18 September 2026.

**Which products and versions are affected?** FluidSynth 2.5.0 to 2.5.5.

**Is there a fix for CVE-2026-61723?** A patch was published on 2026-07-04: Version 2.5.6 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-61723 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-61723?** Check whether you run FluidSynth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The native DLS parser fails to check for integer overflow when computing the chunk size using the expression cues * 4 + cbsize, where cues is read from an untrusted DLS file. An attacker can supply a large cues value that wraps the 32-bit arithmetic, bypassing the bounds check and causing subsequent resize operations to request gigabytes of memory and read invalid memory beyond chunk boundaries. The vulnerability exists only when the enable-native-dls option is enabled.

## Affected products

- FluidSynth FluidSynth 2.5.0 to 2.5.5

## Timeline

- 2026-09-18: disclosed
- 2026-07-04: patched: Version 2.5.6 released with fix

## References

- [https://github.com/FluidSynth/fluidsynth/commit/a2ab32b9c3b9f8845b7254adea73c211f6c5a24c](https://github.com/FluidSynth/fluidsynth/commit/a2ab32b9c3b9f8845b7254adea73c211f6c5a24c)
- [https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6](https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6)

## Related threats

- [FluidSynth DLS articulation chunk integer overflow](https://junglewise.ai/threats/cve-2026-61722-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth DLS loader buffer overrun in sample loop processing](https://junglewise.ai/threats/cve-2026-61721-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth SF2 DMOD chunk integer underflow](https://junglewise.ai/threats/cve-2026-61720-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth heap buffer overflow in MIDI player channel indexing](https://junglewise.ai/threats/cve-2026-61714-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)
- [FluidSynth heap buffer overflow in pitch_bend_range command](https://junglewise.ai/threats/cve-2026-58264-fluidsynth-is-a-software-synthesizer-based-on-the-soundfont-2)