CVE-2026-61722

Name	CVE-2026-61722
Description	FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS parser validates articulation chunks using the unsigned expression cbsize + connblocks * 12 without first ensuring that the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large connblocks value that wraps the expression and bypasses the chunk-size check, after which the parser performs approximately one billion 12-byte iterations beyond the chunk boundary. The excessive processing and invalid reads can cause denial of service. Builds with the CMake option enable-native-dls set to OFF do not expose the 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-hp72-35pr-6h6r
Introduced with: https://github.com/FluidSynth/fluidsynth/commit/c959f8d208bbad9e396dfb745285806b5a4c5a07 (v2.5.0)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/4d7084fca7c876f5d738498b4917a39faf603425 (v2.5.6)