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Vulnerability record · CVE-2026-61721 · published 18 September 2026

CVE-2026-61721: Heap-based buffer overflow vulnerability

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.

8.0 CVSS 3.1 High EPSS 0.19% · top 92.1% CWE-122 · Heap-based buffer overflowCWE-125 · Out-of-bounds read Awaiting Analysis
8.0CVSS 3.1 base score
0.19%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
23 Sep 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

References

LinkTags
https://github.com/FluidSynth/fluidsynth/commit/2354c2a9acdb26de7cdcd37c903ee108f46c0a7d
https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6
https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-59ph-rx8r-8p4j

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Source: NIST National Vulnerability Database (record CVE-2026-61721), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.