Integer Underflow Affecting fluidsynth package, versions <2.5.6+dfsg-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-FLUIDSYNTH-18292076
- published24 Jul 2026
- disclosed18 Sept 2026
Introduced: 24 Jul 2026
CVE-2026-61720 (opens in a new tab)How to fix?
Upgrade Debian:unstable fluidsynth to version 2.5.6+dfsg-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream fluidsynth package and not the fluidsynth package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.