CVE-2025-68617

Name	CVE-2025-68617
Description	FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From versions 2.5.0 to before 2.5.2, a race condition during unloading of a DLS file can trigger a heap-based use-after-free. A concurrently running thread may be pending to unload a DLS file, leading to use of freed memory, if the synthesizer is being concurrently destroyed, or samples of the (unloaded) DLS file are concurrently used to synthesize audio. This issue has been patched in version 2.5.2. The problem will not occur, when explicitly unloading a DLS file (before synth destruction), provided that at the time of unloading, no samples of the respective file are used by active voices. The problem will not occur in versions of FluidSynth that have been compiled without native DLS support.
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)	bullseye	2.1.7-1.1	vulnerable
	bookworm	2.3.1-2	vulnerable
	trixie	2.4.4+dfsg-1+deb13u1	vulnerable
	forky, sid	2.5.1+dfsg-2	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
fluidsynth	source	(unstable)	(unfixed)

Notes

https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-ffw2-xvvp-39ch
https://github.com/FluidSynth/fluidsynth/issues/1717
https://github.com/FluidSynth/fluidsynth/issues/1728
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/92f81cb3b8e02dcb78888bd4dfb9e61076c33c34 (v2.5.2)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/ca2f65dcfaff7f69e5bb9fee311798a6a35443e0 (v2.5.2)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/962b9946b5cb6b16f0c08b89dd1b7016d4fce886 (v2.5.2)