CVE-2025-68617
Use after free in fluidsynth
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.0
Use after free in fluidsynth
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.
- Record
CVE-2025-68617- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
EUVDEUVD-2025-205027
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 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.
- Record
EUVD-2025-205027- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
NVD
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 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.
- Record
CVE-2025-68617- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
OSV
7.0
Use after free in fluidsynth
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.
- Record
CVE-2025-68617- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2025-68617
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 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.
- Record
DEBIAN-CVE-2025-68617- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-68617
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 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.
- Record
UBUNTU-CVE-2025-68617- CVSS 3.1
- 7.0 High
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVopenSUSE-SU-2026:10004-1 No score
fluidsynth-2.5.2-1.1 on GA media
These are all security issues fixed in the fluidsynth-2.5.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:10004-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
fluidsynthDebian:14 |
before 2.5.2+dfsg-1, plus listed versions 2.4.4+dfsg-12.4.6+dfsg-12.4.7+dfsg-12.4.7+dfsg-22.4.8+dfsg-12.5.0+dfsg-12.5.1+dfsg-12.5.1+dfsg-2 |
2.5.2+dfsg-1 |
fluidsynthUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 1.1.6-21.1.6-2ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.1.6-2build11.1.6-31.1.6-3ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.1.6-41.1.8-11.1.8-21.1.8-31.1.9-11.1.9-1ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 1.1.11-41.1.11-4ubuntu12.1.0-12.1.1-22.1.1-2ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 2.1.7-1.12.2.4-22.2.5-12.2.5-1ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 2.3.3-2.12.3.4-12.3.4-1build12.3.4-1build22.3.4-1build32.3.4-1ubuntu0.1~esm1 |
None known |
fluidsynthUbuntu:25.10 |
All versions, plus listed versions 2.4.4+dfsg-12.4.7+dfsg-12.4.7+dfsg-2 |
None known |
fluidsynthUbuntu:26.10 |
All versions, plus listed versions 2.4.8+dfsg-12.5.6+dfsg-12.5.7+dfsg-12.6.0+dfsg-1 |
None known |
fluidsynthUbuntu:Pro:26.04:LTS |
All versions, plus listed versions 2.4.7+dfsg-22.4.8+dfsg-12.4.8+dfsg-1ubuntu0.1~esm1 |
None known |
fluidsynthopenSUSE:Tumbleweed |
before 2.5.2-1.1 | 2.5.2-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-68617 is a high vulnerability (CVSS 7.0) in Fluidsynth, published December 23, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 11th percentile. Fixed in fluidsynth 2.5.2+dfsg-1.
References
github.com/FluidSynth/fluidsynth/security/advisories/GHSA-ffw2-xvvp-39ch
github.com/FluidSynth/fluidsynth/issues/1717
github.com/FluidSynth/fluidsynth/issues/1728
github.com/FluidSynth/fluidsynth/commit/685e54cdc44911ace31774260bd0c9ec89887491
github.com/FluidSynth/fluidsynth/commit/962b9946b5cb6b16f0c08b89dd1b7016d4fce886
github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68617.json