CVE-2026-61723

Name	CVE-2026-61723
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 ptbl chunks with the unsigned expression cues * 4 + cbsize without checking whether the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large cues value that wraps the expression and passes the chunk-size check, causing poolcues.resize(cues) to request approximately four gigabytes and the parser to read billions of entries beyond the chunk boundary. The excessive allocation and invalid reads can cause denial of service. Builds with enable-native-dls set to OFF are not exposed. 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-r4mc-v3p8-pv47
Introduced with: https://github.com/FluidSynth/fluidsynth/commit/c959f8d208bbad9e396dfb745285806b5a4c5a07 (v2.5.0)
Fixed by: https://github.com/FluidSynth/fluidsynth/commit/a2ab32b9c3b9f8845b7254adea73c211f6c5a24c (v2.5.6)