CVE-2026-61721

Name	CVE-2026-61721
Description	FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS loader assigns file-controlled wsmp.loop_start and wsmp.loop_length values to samples without calling fluid_sample_validate() or fluid_sample_sanitize_loop(). A crafted DLS file can place sample loop points beyond the sample buffer, causing out-of-bounds reads during audio rendering, undefined behavior, possible memory disclosure, and denial of service. Builds compiled with the CMake option enable-native-dls set to OFF do not expose the affected parser. 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)

Vulnerable and fixed packages

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
fluidsynth	source	bullseye	(not affected)
fluidsynth	source	bookworm	(not affected)
fluidsynth	source	trixie	(not affected)
fluidsynth	source	(unstable)	2.5.6+dfsg-1

Notes

[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-59ph-rx8r-8p4j
Introduced with: https://github.com/FluidSynth/fluidsynth/commit/c959f8d208bbad9e396dfb745285806b5a4c5a07 (v2.5.0)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/2354c2a9acdb26de7cdcd37c903ee108f46c0a7d (v2.5.6)