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Vulnerability · Published Dec 23, 2025 · Assigned by GitHub_M

CVE-2025-68617Use after free in fluidsynth

High 7.0

In plain English

A high-severity use-after-free in fluidsynth from FluidSynth. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.0High
Exploit odds (30 days)0.2%top 88.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:14fluidsynth2.5.2+dfsg-1DEBIAN-CVE-2025-68617
Ubuntu:25.10fluidsynthno fix listedUBUNTU-CVE-2025-68617
Ubuntu:26.10fluidsynthno fix listedUBUNTU-CVE-2025-68617

Affected products (as reported)

VendorProductVersions
FluidSynth fluidsynth >= 2.5.0, < 2.5.2

Weakness: CWE-416 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

References