CVE-2026-58264 FluidSynth: Heap-based buffer overrun
An out-of-bounds heap write in FluidSynth's command handler allows remote attackers to cause denial of service or execute code when the TCP server is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-58264?
CVE-2026-58264 is a critical memory corruption vulnerability in fluidsynth, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 1.1.2 until 2.5.6, the FluidSynth command handler accepts a pitch_bend_range command whose channel argument is not bounds checked before the supplied value is written through the selected synth channel. An out-of-range channel can therefore cause an out-of-bounds heap write, leading to denial of service or possible code execution. The issue is remotely reachable when the TCP server is enabled through new_fluid_server() or fluidsynth -s, and it is locally reachable through malicious commands delivered to the FluidSynth shell on standard input. Applications that do not use the shell, command handler, or TCP server are not affected. This issue is fixed in version 2.5.6.
Weakness: CWE-122
Which versions are affected by CVE-2026-58264?
Linux distribution packages (1)
fluidsynth openSUSE:Tumbleweed | All versions | 2.5.6-1.1 |
How do I fix CVE-2026-58264?
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-2026-58264 being exploited?
There is no known exploitation of CVE-2026-58264 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-58264, ECHO-c5c2-10b5-9d2d, GHSA-mqmq-w63q-cj94, OESA-2026-2959, OESA-2026-2960, OESA-2026-2961 and 3 more.