What’s Vulnerable › Vulnerabilities

CVE-2021-21417: Use after free in fluidsynth

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-04-29 · updated 2026-06-17
• Weakness: CWE-416

Description

fluidsynth is a software synthesizer based on the SoundFont 2 specifications. A use after free violation was discovered in fluidsynth, that can be triggered when loading an invalid SoundFont file.

Affected products

• Debian Linux: 9.0
• fluidsynth: before 2.1.8 — fixed in 2.1.8

How to fix

Upgrade to a fixed version: fluidsynth 2.1.8. Check the vendor advisory for mitigations.

References

• https://github.com/FluidSynth/fluidsynth/issues/808
• https://github.com/FluidSynth/fluidsynth/pull/810
• https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-6fcq-pxhc-jxc9
• https://lists.debian.org/debian-lts-announce/2021/06/msg00027.html
• https://github.com/FluidSynth/fluidsynth/issues/808
• https://github.com/FluidSynth/fluidsynth/pull/810
• https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-6fcq-pxhc-jxc9
• https://lists.debian.org/debian-lts-announce/2021/06/msg00027.html

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