# CVE-2025-68617: Use after free in fluidsynth

> A race condition in FluidSynth during DLS file unloading can cause a use-after-free, potentially leading to code execution or crashes.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Dec 2025
- **Updated:** 24 Dec 2025
- **Also known as:** DEBIAN-CVE-2025-68617, GHSA-ffw2-xvvp-39ch, UBUNTU-CVE-2025-68617, openSUSE-SU-2026:10004-1

## What is CVE-2025-68617?

CVE-2025-68617 is a high-severity use after free vulnerability in fluidsynth, published on 23 Dec 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### 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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-68617?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `fluidsynth` | openSUSE:Tumbleweed | All versions | 2.5.2-1.1 |

Products: Fluidsynth Fluidsynth.

## How do I fix CVE-2025-68617?

Upgrade to a fixed version.

## Is CVE-2025-68617 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-68617 exists.

## Other vulnerabilities in fluidsynth

- [CVE-2025-56225](https://insights.sbomify.com/CVE-2025-56225/): Null dereference in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68617 and fix it if it is affected.

What it is: CVE-2025-68617 is a high-severity use after free vulnerability in fluidsynth, published on 23 Dec 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-68617 exists.

Affected product: fluidsynth. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-68617/ (Markdown: https://insights.sbomify.com/CVE-2025-68617/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68617
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68617
- OSV: https://osv.dev/vulnerability/CVE-2025-68617

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68617/
Summaries are generated and may contain mistakes; the official description above is the record.