CVE-2025-68617: Use after free in fluidsynth

Published Dec 23, 2025
·
Updated

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.

Affected Software

2 affected components
fluidsynth fluidsynth>=2.5.0<2.5.2
fluidsynth fluidsynth>=2.5.0<2.5.2

Event History

Dec 23, 2025
CVE Published
via MITRE·10:41 PM
Data Sourced
via MITRE·10:41 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·11:15 PM
RemedyDescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2025-68617?

The severity of CVE-2025-68617 is considered to be significant due to the risk of heap-based use-after-free vulnerabilities allowing potential exploitation.

2

How do I fix CVE-2025-68617?

To fix CVE-2025-68617, users should update FluidSynth to version 2.5.2 or later to mitigate the vulnerability.

3

What versions of FluidSynth are affected by CVE-2025-68617?

FluidSynth versions from 2.5.0 up to but not including 2.5.2 are affected by CVE-2025-68617.

4

What type of vulnerability is CVE-2025-68617?

CVE-2025-68617 is a race condition that results in a heap-based use-after-free vulnerability.

5

Can CVE-2025-68617 be exploited remotely?

CVE-2025-68617 can lead to potential exploits if an attacker can trigger the race condition while manipulating DLS files.

Contact

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