CVE-2026-111123

FluidSynth through 2.6.1 Out-of-Bounds Write via SoundFont Modulator Destination

State: Published
Severity: 6.9 Medium
Published: Oct 15, 2026
Updated: Oct 15, 2026
Reserved: Oct 15, 2026

Description

FluidSynth through 2.6.1 contains an out-of-bounds write vulnerability that allows attackers to corrupt heap and stack memory by supplying unvalidated SoundFont modulator destination values. Attackers can craft an SF2 file with PMOD/IMOD destinations of 63 to 255 that, when loaded and played, write past the voice generator array and updated_gen_bit, causing memory corruption and crashes.

Scores

CVSS	Score	Vector	Source
4.0	6.9 Medium	CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N	VulnCheck
3.1	6.1 Medium	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H	VulnCheck

Weaknesses

CWE-787 Out-of-bounds Write

Affected Products

Product	Versions
fluidsynthFluidSynth	2.6.1 and earlierAffected

References

https://hackmd.io/@haind-pwn/fluidsynth-sf2-modulator-dest-generator-oob-writetechnical-description
https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/synth/fluid_voice.c#L615-L623technical-description
https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/synth/fluid_voice.c#L1184-L1229technical-description
https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/sfloader/fluid_defsfont.c#L1609-L1611technical-description
https://github.com/FluidSynth/fluidsynthproduct
VulnCheck Advisory: FluidSynth through 2.6.1 Out-of-Bounds Write via SoundFont Modulator Destinationthird-party-advisory

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