CVE-2026-61720
FluidSynth: SF2 DMOD Chunk Unsigned Underflow
- State
- Published
- Severity
- 6.2 Medium
- Published
- Sep 18, 2026
- Updated
- Sep 21, 2026
- Reserved
- Jul 10, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.2 Medium | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
- CWE-191 Integer Underflow (Wrap or Wraparound)
Affected Products
| Product | Versions |
|---|---|
fluidsynthFluidSynth |
|
References
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