Description
FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the SF2 parser computes the DMOD modulator count as chunk.size / SF_MOD_SIZE - 1 without rejecting chunks smaller than one record. A crafted SF2 file containing a zero-sized DMOD chunk makes the unsigned subtraction wrap to UINT_MAX, and the parser then attempts billions of SFMod allocations. This exhausts process memory and causes denial of service. No workaround is available. This issue is fixed in version 2.5.6.
Published: 2026-09-18
Score: 6.2 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Description FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the SF2 parser computes the DMOD modulator count as chunk.size / SF_MOD_SIZE - 1 without rejecting chunks smaller than one record. A crafted SF2 file containing a zero-sized DMOD chunk makes the unsigned subtraction wrap to UINT_MAX, and the parser then attempts billions of SFMod allocations. This exhausts process memory and causes denial of service. No workaround is available. This issue is fixed in version 2.5.6.
Title FluidSynth: SF2 DMOD Chunk Unsigned Underflow
Weaknesses CWE-191
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-18T20:03:43.989Z

Reserved: 2026-07-10T18:51:13.920Z

Link: CVE-2026-61720

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-18T20:17:18.420

Modified: 2026-09-18T20:17:18.420

Link: CVE-2026-61720

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-191

    Integer Underflow (Wrap or Wraparound)