CVE-2026-61723 Details
Description
FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS parser validates ptbl chunks with the unsigned expression cues * 4 + cbsize without checking whether the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large cues value that wraps the expression and passes the chunk-size check, causing poolcues.resize(cues) to request approximately four gigabytes and the parser to read billions of entries beyond the chunk boundary. The excessive allocation and invalid reads can cause denial of service. Builds with enable-native-dls set to OFF are not exposed. This issue is fixed in version 2.5.6.
A denial-of-service vulnerability has been identified in FluidSynth versions 2.5.0 prior to 2.5.6. The issue arises in the native DLS parser, which improperly validates ptbl chunk data. The parser allows a crafted DLS file to bypass chunk-size checks by supplying a large cues value that causes an integer overflow. This exploitation leads to excessive memory allocation of approximately four gigabytes and allows the parser to read billions of entries beyond the chunk's actual boundary, causing invalid memory access. The vulnerability is not present in builds with native DLS support disabled.
Users can update to FluidSynth version 2.5.6 to address this vulnerability. If FluidSynth is compiled with CMake, the native DLS feature can be disabled to avoid exposure to this issue.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 18, 2026CISA-ADP
Assessed Sep 21, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/FluidSynth/fluidsynth/commit/a2ab32b9c3b9f8845b7254adea73c211f6c5a24c | [email protected] | Source CodeVendor |
| https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6 | [email protected] | BundleRelease NotesVendor |
| https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-r4mc-v3p8-pv47 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-190 | Integer Overflow or Wraparound | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| FluidSynth | >= 2.5.0, <= 2.5.5 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 21, 2026 | CVE Modified | CISA-ADP |
| Sep 18, 2026 | New CVE Received | [email protected] |