CVE-2026-61721 FluidSynth: Heap-based buffer overrun for DLS samples
A crafted DLS file can cause out-of-bounds reads in FluidSynth, leading to memory disclosure or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61721?
CVE-2026-61721 is a high-severity memory corruption vulnerability in fluidsynth, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS loader assigns file-controlled wsmp.loop_start and wsmp.loop_length values to samples without calling fluid_sample_validate() or fluid_sample_sanitize_loop(). A crafted DLS file can place sample loop points beyond the sample buffer, causing out-of-bounds reads during audio rendering, undefined behavior, possible memory disclosure, and denial of service. Builds compiled with the CMake option enable-native-dls set to OFF do not expose the affected parser. This issue is fixed in version 2.5.6.
Which versions are affected by CVE-2026-61721?
How do I fix CVE-2026-61721?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-61721 being exploited?
There is no known exploitation of CVE-2026-61721 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-61721, GHSA-59ph-rx8r-8p4j.