CVE-2025-68617: FluidSynth is a software synthesizer based on the SoundFont 2 specifications

Routine

HIGH 7.0UPGRADE

CVE-2025-68617 is a high-severity flaw (CVSS 7.0) affecting fluidsynth. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.0 (High)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 88%)
CISA exploited list	No
Weakness	CWE-416
Published	2025-12-23
Last modified	2026-10-19

Publisher (CNA): GitHub, Inc. · Vendor: fluidsynth

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-12-23 23:15 UTCPublished CVE record published
2026-10-19 22:10 UTCUpdated Record last modified

fluidsynth fluidsynth UPGRADE

Affected: >= 2.5.0 and < 2.5.2

Fixed in: 2.5.2

Safe to downgrade to: a release before 2.5.0

1. Check installed version

apt-cache policy fluidsynth || rpm -q fluidsynth || fluidsynth --version

2. UPGRADE to 2.5.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fluidsynth

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fluidsynth

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.5.0 (Debian / Ubuntu)

apt-cache madison fluidsynth sudo apt install fluidsynth=<VERSION_BEFORE_2.5.0> sudo apt-mark hold fluidsynth

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fluidsynth sudo dnf downgrade fluidsynth-<VERSION_BEFORE_2.5.0> sudo dnf versionlock add fluidsynth

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-68617?

fluidsynth: upgrade to 2.5.2. Exact commands for each OS are on this page.

Is CVE-2025-68617 being exploited?

CVE-2025-68617 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-68617 affect?

CVE-2025-68617 affects fluidsynth. Severity is high (CVSS 7.0). 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

How urgent is CVE-2025-68617?

Priority 32/100. High severity; Public exploit reference

Related CVEs

CVE-2025-56225 HIGH 7.5 UPGRADE fluidsynth-2.4.6 and earlier versions is vulnerable to Null pointer dereference in fluid_synth_monopoly.c, tha

References

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