CVE-2026-61721: Fluidsynth · 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
Affects fluidsynthSource GCVE Database
Not known to be exploited · CVSS 8.0 High · fixed in 2.5.6 : patch fluidsynth soon.
Data as of 8 Nov 2026, 23:24 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.5.6
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 18 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 20.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Ubuntu 18.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=bionicOther threats | Affected
| Fixed in– |
Ubuntu 16.04 LTSfluidsynthpkg:deb/ubuntu/fluidsynth?arch=source&distro=xenialOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade FluidSynth to version 2.5.6 or later, where this vulnerability is fixed. Alternatively, builds compiled with the CMake option enable-native-dls set to OFF are not affected by this issue. Users should verify their build configuration or apply the official update to remediate the vulnerability.
Description
FluidSynth versions from 2.5.0 up to but not including 2.5.6 contain a vulnerability in the native DLS loader where file-controlled wsmp.loop_start and wsmp.loop_length values are assigned to samples without proper validation. This can lead to out-of-bounds reads during audio rendering, causing undefined behavior, potential memory disclosure, and denial of service. The issue does not affect builds compiled with the CMake option enable-native-dls set to OFF. The vulnerability is fixed in version 2.5.6.