Buffer overflow in Fluidsynth

CVE-2026-61714

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.2.4 until 2.5.6, configuring synth.midi-channels above 16 allows the MIDI player to index _fluid_player_t::channel_isplaying outside its fixed-size heap allocation while tracking active channels. The resulting out-of-bounds reads and writes invoke undefined behavior and may compromise confidentiality, integrity, or availability. No crafted MIDI file is required because the unsafe condition is created by the channel-count configuration itself. Keeping synth.midi-channels at its default value of 16 avoids the vulnerable path. This issue is fixed in version 2.5.6.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.001 (3.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 3.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-61714: held from 0.002 to 0.001.

EPSS over last 30 days · oldest: 0.002 · newest: 0.001 · change: -0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-61714?
CVE-2026-61714 is a high-severity vulnerability in Fluidsynth, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-09-18.
How severe is CVE-2026-61714?
High severity. CVSS v3 base score is 7.8 out of 10.