CVE-2026-111123: Memory Corruption (CVSS 6.1)

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.

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CVSS v3.1 Score

6.1

MEDIUM

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

Weakness Type (CWE)

CWE-787 Out-of-bounds Write

References

Other References

https://github.com/FluidSynth/fluidsynth https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/sfloader/fluid_defsfont.c#L1609-L1611 https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/synth/fluid_voice.c#L1184-L1229 https://github.com/FluidSynth/fluidsynth/blob/71e85b2ca6bf48641ba7e2261d8f2640ae473773/src/synth/fluid_voice.c#L615-L623 https://hackmd.io/@haind-pwn/fluidsynth-sf2-modulator-dest-generator-oob-write https://www.vulncheck.com/advisories/fluidsynth-through-2.6.1-out-of-bounds-write-via-soundfont-modulator-destination https://hackmd.io/@haind-pwn/fluidsynth-sf2-modulator-dest-generator-oob-write

Frequently Asked Questions

What is CVE-2026-111123? +

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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-111123? +

CVE-2026-111123 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-111123? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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