| Name | CVE-2026-61720 |
| 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| fluidsynth (PTS) | bookworm | 2.3.1-2 | fixed |
| trixie | 2.4.4+dfsg-1+deb13u3 | fixed | |
| forky, sid | 2.6.0+dfsg-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| fluidsynth | source | bullseye | (not affected) | |||
| fluidsynth | source | bookworm | (not affected) | |||
| fluidsynth | source | trixie | (not affected) | |||
| fluidsynth | source | (unstable) | 2.5.6+dfsg-1 |
[trixie] - fluidsynth <not-affected> (Vulnerable code introduced later)
[bookworm] - fluidsynth <not-affected> (Vulnerable code introduced later)
[bullseye] - fluidsynth <not-affected> (Vulnerable code introduced later)
https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-rmc4-c8hw-455w
Introduced with: https://github.com/FluidSynth/fluidsynth/commit/9c387006c2e09e32e0fdc35cdd4370b89edc969b (v2.5.0)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44 (v2.5.6)