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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| FluidSynth | fluidsynth | >= 2.5.0, < 2.5.6 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | fluidsynth | 2.5.6+dfsg-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | fluidsynth | No fix yet | — |
| Ubuntu Pro 24.04 LTS | fluidsynth | No fix yet | — |
| Ubuntu Pro 22.04 LTS | fluidsynth | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | fluidsynth | No fix yet | — |
| Ubuntu Pro 18.04 LTS | fluidsynth | No fix yet | — |
| Ubuntu Pro 16.04 LTS | fluidsynth | No fix yet | — |
| Ubuntu Pro 14.04 LTS | fluidsynth | No fix yet | — |